Rare Random Drop

In a game with Random Drops, the one that will refuse to appear. A Random Drop with a very low probability, something that frustrates the player that tries to get it.

The range in which a drop becomes a Rare Random Drop can vary widely. Depending on the game, the common drop may have a 70% chance and the "rare" a 30% chance; in others the rare drop may be a 1 in 1000 chance, or even worse. In any case it usually means that you'll spend hours killing monsters until you get it, which can be bad if you just want the object, but it's worse if you need the object to continue with the game.

Sometimes a Rare Random Drop applies to a boss and you have to endure the same fifteen minute battle (and accompanying cutscenes) over and over again until you get lucky. Bonus if the boss in question is That One Boss, and you barely survived the first time you killed it. Fortunately game designers usually don't make the dropped object an absolute necessity in such cases, so unless you really want the object there will be no need to go through the fight again.

If you're lucky, there'll be an item or special method that increases your chances of getting these drops, but there's the chance, if it is an item, that that item is a Rare Random Drop too. Have fun getting 100% Completion if there is no way to improve your chances.

While it's called Rare Random Drop, the trope also applies to objects found in chests, treasure and other random things where the chances are very low, but those cases aren't as prominent as the Random Drop implementation.

Related to Luck-Based Mission. In MMORPGs, if players fight among themselves to get one of these it becomes Loot Drama. If you need lots of dedicated item-hunting to get anything remotely fun, see Earn Your Fun.

Action Adventure

 * The Castlevania series has a lot of examples:
 * Castlevania: Curse of Darkness has any number of items that only very rarely drop from enemies. This is the only way to acquire many of the materials needed to make weapons and armor. However, most of the materials can be stolen from other enemies, so it's not quite so bad. That being said, since stealing in this game works by locking onto an enemy, waiting for them to do a specific action that leaves them open for stealing, getting right next to them and then pressing a button, some of the items can be even more of a pain in the ass if you can only steal their item with a ridiculously good timing, using obscure gimmicks or avoiding a hard-to-dodge attack with perfect timing and be positioned correctly right afterwards.
 * Castlevania: Circle of the Moon was particularly egregious in two respects. There is an item that increases the rate of random drops, but this item was also a random drop. There's also a spell that boosts your luck (and thus increasing your odds of getting a random drop), but to get the materials for the spell you needed two random drops (although the odds of getting those drops was much more realistic—no worse than a 10% chance). Remember too, in this game there is no other way to get any items other than through random drops. Even the most basic Potion is a rare drop from just a handful of enemies. The people who made this game hate you and your family.
 * Even worse is the skeleton athlete. It drops the rare bear ring, but in order to get it, you have to kill it before it commits suicide and there is no feasible way to kill it other than to use the Speed boost skill. Did I mention that you have to STOP to whip? Unless you can kill it with a knife or get lucky enough to actually hit it, you might kill it. But there is no guarantee the item will drop at all.
 * In Aria of Sorrow "Tsuchinoko," which spawns in the far corner of one room maybe half the time, and immediately tries to burrow out of sight, and drops his soul maybe one time in fifty kills. There are other bad ones, but he's the worst. Many players have killed it once out of curiosity after killing the boss before its room, gotten the soul, and wondered if that was actually the boss-fight reward.
 * One of the most aggravating souls to get in Dawn of Sorrow is that of Peeping Eye, whose equippable soul lets you see breakable walls. Even though it wasn't that rare in Aria, in Dawn its base chance of coughing up its soul is 1%. Even if you wait until you can pay Hammer the $300,000 for the Soul Eater Ring (by which point you may have already found most of the breakable walls), it can take hours to get Peeping Eye's soul. Fortunately there is a soul that increases your luck, but it's also a Random Drop (though not as difficult to get as Peeping Eye).
 * This trait even persisted in Portrait of Ruin, where Peeping Eye drops a piece of headgear which reveals breakable walls, but according to one FAQ the base drop rate is an even worse 0.69%! Don't say I didn't warn you.
 * Merman Meat in Order of Ecclesia. This is needed for a sidequest to unlock better healing items at the shop (which you will need), but is a nightmare to get. First you need to intuit which enemy actually drops it, and even then, it's a six-star drop without copious luck boosting.
 * Castlevania: Symphony of the Night has a bunch of really cool (But sometimes impratical) weapons that randomly drop from enemies. Most infamous would be the Crissaegrim that drops at an insanly low rate from one of the game's resident Goddamn Bats. (Though unlike every other goddamned bat these don't spawn nearly as often.) Some locations do allow you to kill enemies with rare drops in rapid succession by switching rooms back and forth quickly if they don't drop the item you want, but that also tends to devolve into a reaction test of actually being able to see the item drop and stop yourself from instinctively changing the room again before picking the said item up, which of course makes it disappear. Not to mention Heaven Knights, which fly around, are unhindered by walls and appear in an area where they can easily drop their rare item in a location where it's impossible to get even if it didn't disappear in 10 seconds or so.
 * Every relic except two in Lament of Innocence are found throughout all the levels, like good hidden items should be. With the exception of two. These two are the rare drops for somewhat difficult to kill monsters and it's rather frustrating to try to obtain them...

Fighting Game

 * In Super Smash Bros.. Melee, there is a 1 in 151 chance of getting Mew from a Poké Ball, and a 1 in 251 chance of getting Celebi. Disappointingly, they only appear and fly away, but reward you with a lot of points, and an alert after the match is done telling that you met them for the first time.
 * This also happens in Super Smash Bros.. Brawl, but with severely decreased chances of getting any legendary Pokémon at all. This being the case, however, most legendary Pokémon are much more lethal; Mew drops CDs, Celebi drops trophies, and Jirachi (who wasn't in Melee) drops a ton of stickers.
 * For all those die-hard completionists, Brawl's Subspace Emissary will be HELL. To get all the trophies in Brawl, you have to play Subspace Emissary, and have a trophy stand randomly drop during all the Boss Battles. When it comes to Meta-Ridley, it's incredibly frustrating - not only is there a time limit on the battle, but unless you have ABSOLUTELY PERFECT timing, the trophy will most likely drop into a bottomless pit if you're not fast enough. Luckily, trophy stands appear much faster in this battle.

First Person Shooter

 * Borderlands is the FPS equivalent of this (its initial pitch: "Halo meets Diablo"). It, too, has a list of super-rare (DLC-exclusive) weapons known as "Pearlescents". These super-strong firearms drop at a rate of 1 for every 60 orange (the previous highest-level category) items. Of course, they're a little more prevalent than you might think, thanks to a multiplayer glitch that allows for easy item duplication.
 * The folks at Valve have decided to throw the unlockable weapons of Team Fortress 2 into this category with rates based on time played, and made the achievements "useless." The first day had absolutely horrendous drop rates, and most of the time it was weapons you already had, so you can imagine how fun that was.
 * Also realize that two of the nine classes had just been provided with unlockable weapons, meaning players had six new toys to earn (three each) and zero ways in which to earn them. The system was so hopelessly broken that Valve has since brought back the achievements. Currently both the broken drop rate and achievement systems are active. Currently, the drop rate is about one an hour, so not so bad.
 * You also can get purely cosmetic hats for the classes. There are 9 classes. Your odds of getting a hat (any hat) is .5%, or 1/200. Your odds of getting a particular hat of 1/1800. To have a 50% chance of getting a particular hat, statistically you need to log 1250 hours. That's 52 days of play. That's more play time than all but ten of the official maps have.
 * The players back lashed by using Steamstats to "simulate idling without actually having the game running." Valve turned around and took away the ill-gotten hats, gave the non-cheaters halos, and then increased the drop rate. You can read all about it here
 * And now with the Engineer Update, Valve has decided to gift 100 Golden Wrenches to the community, which you can find by chance for every time you use the crafting system. Given that well over 20,000 people are playing TF 2 at any given time, and the fact that you need items to craft in order to craft, the chances of finding one of these Wrenches is exceptionally low. This hasn't stopped the community from complaining about it, of course.

Hack And Slash

 * The Diablo games feature items that aren't just randomly dropped, but randomly generated from thousands of potential combinations of attributes, special abilities and base weapon types. Runes (items you can place into other items to make them better) are particularly glaring, with some high-level runes having such tiny chances to drop (1 in millions, and even that requires finding enemies even capable of dropping the runes in the first place) that most hard-core players have never seen a legitimate one (ones created by hacks, of course, are another matter entirely). In fact, one person apparently estimated that one has a better chance of getting hit by a falling plane that was struck by lightning than one does of finding the rarest rune. Nobody knows if that estimation is true, but you get the idea.
 * The rune example is fairly straightforward, but it can get much more complex: A base sword, for example, might have an inherent range of say 5 +/- damage and 10 +/- quality. So, just getting a "max" sword would take at least 15 rolls of that sword, of which, the top swords are also rare. Then, the top prefix is "Cruel," which varies between 200-300% added damage. The top suffix is "of Eviscration" which also varies by 20 points. It is estimated that maybe 1 sword has ever existed that was truly "perfect." You would need 10's of thousands of rolls to get a perfect roll, but you would probably need somewhere around 100 million of that sword to get 10k with that roll to even have a chance at the perfect stats. And then, there's the "Etheral" version, which is 1/3 as common as the regular version. Only 1 300% Cruel, Etheral, Elite class, 2 Socket sword has ever been found.
 * Diablo II includes many items that, when equipped, increase the odds of an item drop, notably socketing an item with perfect topaz gems. Some players traded for as much of this equipment as they could cram onto themselves, and went hunting; the Barbarian had an edge over any other character in this respect, because the optimum item-finding equipment package requires dual-wielding a pair of enchanted broadswords, which only the barbarian can do, and the barbarian had a skill that basically amounted to "trigger the random drop again".
 * Ninety-Nine Nights is a terrible offender in this category, with the final boss being almost unbeatable without an item which randomly drops (Or more likely does not drop) from one of the finite number of enemies within the last level, often forcing you to restart the mission hundreds of times over before it finally drops.

MMORPGs

 * Final Fantasy XI is such an offender that we won't bother to list any of these drops, there are just too many.
 * World of Warcraft is another major offender. No need to add examples, the list would be nearly infinite.
 * Played seriously straight in MMORPG Maple Story. Monsters have a very good chance (roughly 50~75%) of dropping some money (Mesos) and an "ETC" drop unique to the monster (or monster type). They have about a 1-in-10 chance of dropping potions or material ores, a very rare chance of dropping equippable items, and an extremely rare chance of dropping scrolls (which are used to upgrade equipment) or throwing stars. A coupon in the game's cash shop doubles the drop rate of monsters killed by the user. It doesn't help that sometimes only one particular enemy drops a particular item. Or that there's no indication that a miscellaneous drop is needed for a quest you don't have. Or quests that ask you to get an item, but don't say what enemy drops it. Then there's the major bosses Zakum and Horntail, who are guaranteed to drop at least one Zakum Helmet or Horntail Pendant each time they're killed, it's how many that drop that's random. All of their other drops are subject to Random Drops.
 * The Malaysia exclusive map (guess what it's called) has somewhat broken drop rates- i.e. something around twice or thrice that of the original maps. This stacks with the event bonuses.
 * This aspect is where some quests become truly, stupidly hard. For instance, there's one quest where you have to find a little fairy's lost glass slipper. The slipper was stolen by the fire boar enemies in the mountains around Perion. No one is quite sure of the drop rate, but you can stand there and kill - quite literally - thousands upon thousands of fire boars and never see the item.
 * It doesn't help that they randomize the drop rate at least once a week so you can't even figure out what the drop rates are.
 * Phantasy Star Online's most powerful weapons often have drop rates ranging from 1-in-72 to 1-in-22000. Add that to the fact that the 1-in-22000 monsters usually only show up singly, and only in certain map variations...
 * And only for certain characters, as a character gets 1 of 12 possible dropcharts permanently assigned to it upon creation based on the character's names, class, and even gender, with some items having a 1 in 299594 chance from only 1 chart, from 1 monster, that can only be found in 1 area, with the monster being the rare form of an already rare monster.
 * In Anarchy Online the greatest example would be the Sparkling Scimitar of Spetses (a stupidly rare item dropping from a semi-boss from the 2nd hardest area in the known game) is so ridiculously rare that it is counted among the forums. The numbers are kept as to which dimension (of the 3 this game has) has dropped how many... at last count, it was STILL IN THE SINGLE DIGITS for dropping after at least 3-4 (maybe longer) years of play in the game that allowed the zone.
 * EverQuest had some mean ones. One otherwise uninteresting newbie zone had a high-level halfling that spawned every few days in a random location, disappeared after two minutes whether anyone killed her or not, and had a one in eight chance of dropping a very expensive item.
 * In Everquest 2, in most zones, monsters will drop an "exquisite chest" (a chest containing the best kind of treasure, Fabled) 0.0126% of the time. Of course, which Fabled treasure drops depends on random chance and which monster dropped the chest...
 * A staple of Ragnarok Online. Each enemy has a 1/10,000 chance of dropping a "card" (with rare exceptions like porings at 1/1000) which can be permanently placed into a "slotted" weapon or armor, which also have an extremely rare chance of dropping. The cards give bonuses to you when you wear armors with a card equipped. They range from completely useless in the case of most ordinary monster cards, to boss cards which have downright Game Breaking stats such as immunity to spells and abilities. The catch is, since bosses only respawn once per hour in one location, if you were to kill a boss every hour on the hour for a year you would only have a 58% chance to get their card...
 * Due to the way the RNG works in this game, it's actually 1 in 5000. (The RNG can actually hit 0, giving stuff a .01% higher chance to drop.) There's cash shop items to increase this further.
 * Kingdom of Loathing uses this extensively. Fortunately you'll be able to buy some of them, so you can choose to get a lot of money if you don't want to face the odds.
 * Warhammer: Age of Reckoning averts this to a degree. Although there are still random drops, when you get a quest to get, let's say, 10 wolf eyes, at least the game have the decency to give two eyes to most wolves, and no quest has a <1 drop ratio. You also get fairly good items from influence and even better ones for cheap if you have renown, so the rare-drop ones aren't all that needed.
 * Also, many items will drop as broken versions that can be repaired into an item your class can use. Unfortunately this is not true of some of the higher-level set items.
 * City of Heroes has Purple Recipes. These only drop from enemies around 50 (the cap), getting one your character has any use for is another thing entirely, and getting the one you actually want quite the exercise in patience. Thankfully with so many players and a Market, the one you want is usually for sale, and although it'll likely be pretty expensive, the Purple that was trash to you might be a treasure to another.
 * Ace Online has the Boss Armors. The items needed to craft them come from bosses that spawn only three times a day in places where you can fight the opposing faction (so you'll probably have to fight them too) with insanely low chances to get them. Not only that, but when you try to combine them there's a 50% chance of failure and you lose the items if that happens. There are more examples, but no one is as insane as this one.
 * The Episode 3 Part 1 however, makes it somewhat easier; there're three bosses in Pandea Maps that can drop any one of the unfinished boss armor. The corresponding item has the same quirk. There's only one slight problem; the entire Pandea maps are Scrappy Levels made of aggro, aggro, and... more aggro. And more aggro.
 * RuneScape has too much of this to count; the Draconic Visage from almost all dragons, the godswords from the God Wars Dungeon, various high level armor from boss monsters, the sigils... At least It's one of the best moneymakers in the game. It can get frustrating in that many of the bosses are hard to kill solo and you need a team to effectively farm them. This by itself isn't so bad, but you have 3 options for dividing the loot: Player who deals most damage gets drop, (not very fair) all players get the value in coins divided amongst the group, (Witch can lead to some small payouts) and 1 player gets the drop, while the other players get an increased chance of getting a drop. (This does not always go as planned.)
 * Although this is sort of justified as every drop affects the economy (slightly) each drop. Considering those bosses are killed thousands of times a day (bar the boss that drops the sigils), one of the items being adjusted to drop a little too much would make them a lot cheaper.
 * "Dynasty Warriors: online" has such a horrible way to deal with its Random Drops that if you want something special you’ll probably have to deal with this trope.

Roguelike

 * In Nethack this trope is primarily averted: every enemy will drop everything it carries upon death, and maybe something else that it wasn’t carrying too.
 * Ancient Domains of Mystery. Many items that are important for various quests (notably the amulet of life saving) are random drop items. Where the Creator really extracts the urine is when you are required to find a boar skull as part of the Ultra ending quest. Said boar is only encountered infrequently, is in the highly-dangerous overworld and even then rarely leaves a skull. Low-to-mid-level players frequently starve to death or spend 60-320 game days trying. Higher-level players resort to dooming themselves to increase the encounter rate, or hunting for an item that grants one wish (also only available by random drop, and extremely rare).

Role Playing Game

 * Final Fantasy IV. Two words: Pink Tails. They are held by one enemy, found in one room, with approximately a 1-in-64 chance of encountering it and a 1-in-64 chance of dropping the proper loot once defeated—and that's the only way to get the best armor in the game. For those of you who didn't study math, that's a whopping 1-in-4096 chance per encounter. Alarm clocks trigger an encounter with them 100% of the time though, but you can only carry 99 of them.
 * Additional...fun in relation to pink tails. The only way to find the monsters that drop it in the DS remake is to use an Alarm item. Otherwise the room is completely clear of random encounters. So, at least now you have a 100% chance of encountering the enemy, right? Well, you now have a 1/64 chance of the Princess Flan dropping any item AT ALL, and a 1/64 chance of it being a Pink Tail. So the odds are the same (1/4096). And since you can only carry 99 of them you’ll have to travel a lot to the shop in order to replenish.
 * In the DS version Rainbow Puddings are quite difficult to get too.
 * FFIV's sequel, The After Years averts this thanks to an item that changes the rare drop to the next item on the rarity list. Due to how the Random Drop system works you’ll probably get more rare items than normal ones.
 * Played straight in the PSP collection, where the random drops are actually random again, but averted slightly in that it's more likely you get rare items from the Challenge Dungeon boss chests that are randomized. The worst item you can get is an X-Potion: however, you can't get any extra copies of any of the items, including Adamantines that're used to trade them for parts of Armor of Invincibility at the end of the game.
 * Final Fantasy V, like the other Final Fantasy games, has several rare drops. The Tinklebell is the most annoying, and belongs to Twintania. It's technically a 1/16 drop ratio, but Twintania's drops change based on whether it's in Normal form, or if it's in its Gigaflare form. The Normal form is the harder to kill of the two, and is the form that drops the Tinklebell.
 * Final Fantasy VI gave you a consolation prize in the form of common drops being guaranteed if you didn’t get the rare one.
 * Final Fantasy XII took things to somewhat ridiculous length: not only does every monster have common, uncommon, rare and ultra-rare random drops (and a fifth class of drop that requires you to purchase a 'monograph' describing that class of monster), but also (different!) lists of random steals and 'poaches'. Crafting Tournesol, the game's Infinity+1 Sword, requires multiples of the rarest loots from the rarest monsters.
 * Let us not forget that the vast majority of treasure boxes in Final Fantasy XII were random drops; sometimes, the chest wouldn't be there, and most of the time, all the treasure you'd get from most boxes was a paltry sum of Gil. Worse, there were 4 chests that were fixed to cause the Infinity Plus One Spear to become ONLY a random drop, with a chance of 1-in-1000, instead of a sure get from a chest in a Bonus Dungeon.
 * However, a method has been found to trick the game's "pseudo"-RNG into getting a guaranteed Zodiac Spear from the chest in the Henne Mines, so if you know it you can easily get more.
 * Final Fantasy XIII adds the notoriously uncommon Trapezohedron to this growing list of epic loot. The Traps are extremely rare items that only drop once in a blue moon from an Adamantoise, which is basically a Bonus Boss for all intents and purposes - and one that requires extensive planning, preparation, and Level Grinding to defeat. (Or Death spamming, if you're willing to put up with the antics of the Random Number God.) Many players have killed several dozen of these absurdly tough enemies without getting a single Trap, which is needed to upgrade your Infinity-1 Sword to an Infinity+1 Sword.
 * In the Rune Factory game series Item Crafting is a major part of the game. To create the vast majority of powerful equipment and potions requires many battles with the various monsters, to get the Randomly Drops components you need.
 * Persona 3 has Elizabeth's requests, in which she usually asks you to kill a specific enemy and bring back a number of parts from it. The trick is that if you don't kill the enemies with the protagonist, the item drop rate is extremely low.
 * FES corrected this: if you kill at least one monster of the required type in a battle, you'll always get at least one item of the required type, guaranteed, though at the expense of other possible drops.
 * EarthBound. Its 1-in-128 items have become the focal point of several fan quests
 * Mother 3 is a bit nicer, with a 3% to 5% chance of getting good weapons from certain enemies.
 * The Breath of Fire series. Numerous examples of this.
 * Pokémon has the unique problem in that the frustration-causing random drop is more often than not the Pokémon themselves. Some appear very rarely in the wild, with 1-in-20 odds or worse. The frustration is compounded by the fact that you have to weaken these monsters without defeating them, as well as hoping they've got the right gender, nature, etc. Chansey (and the Lucky Egg it may carry), Feebas (which only appears in 6 or 4 fishing tiles depending on the game, out of 212 or 50) and Munchlax (0,93% chance of appearing in 4 specific Honey Trees) are the most famous ones.
 * Shiny Pokémon only have a one in 8192 chance. Legendary Pokémon and starters can be Shiny as well, so start breaking in (or outright breaking) your soft reset fingers! Luckily, like the item example above, Generation IV introduced ways to boost this probability.
 * Don't forget the Pokérus! Each encounter has a 1 in 21,845 chance of giving it to you (in Gold and Silver). Luckily you don't have to catch it for it to spread, just battle, and it can spread to the rest of your team after getting it. It will double the amount of Effort points you get in each battle.
 * The enigmatic Mirage Island of Ruby/Sapphire/Emerald! Every day a number between 0 and 65535 is generated. In order to access the island, you have to have a Pokémon in your party with a personality value that matches the number of the day. Did we mention that the Personality Value of a Pokémon can be anywhere from 0 to 4,294,967,295? The only thing worthwhile about Mirage Island is a particularly rare berry tree.
 * Pickup is an ability that gives you an object 10% of the time after a battle. It’s charts can give you tons of different useful objects depending on your level, but their chances range from 50% of the common ones to 1% of the rare ones, which include Rare Candies and T Ms.
 * In Wizardry 7 many good drops (in early game it's mostly good weapons/armor) have low rates, and/or drops randomly select from a list with cheap (Potion of Lt. Heal, bite daggers) and good (cure poison, poison darts) items, so grinding random encounters in hope to get some good loot is not unusual. Chests are randomized, too.
 * In Wizardry 8 enemy drops and chest contents are determined when loading an area. So after a 15-minute fight, if the monster doesn't drop Excalibur, you can't just reload and fight again. You have to reload from before you entered the area, then make it all the way back to the monster, then fight it again.
 * Golden Sun series can either work this way or the opposite, thanks to how easily you can manipulate the RNG.
 * The World Ends With You seems to be initially guilty of this, but one of the things you actually learn about in the game is to manipulate the drop rates (which are shown in the bestiary) to the point that even the rarest ones (there’s one that is only dropped 0,03% of the time) become guaranteed drops. The drawback is that you’ll have to drop down your level and chain multiple battles, sometimes with bosses included, in order to do that. And the only way to get rid of the drawback is… you guessed it: get a lot of those rare drops, so it can be useless after you get 100% Completion.
 * Mega Man Battle Network series brings this with the Mega chips (you’ll have to fight bosses a lot) and the Program Advances.
 * It’s successor, Mega Man Star Force, does it too.
 * Monster Hunter has tons and tons of drops, but the most rare ones will inevitably be those that the most difficult bosses have. Lao-Shan Ruby and the Big Elder Dragon Jewels are famous ones.
 * Carried over for the Crossover in Metal Gear Solid: Peace Walker. Rathalos drops plans for the Taneshigama, one of the most useful weapons in the game, and Tigrex and Gear Rex drop parts of the most powerful Co-op weapon in the game. With a 1% chance. Enjoy your grind.
 * In Kingdom Hearts coded this can happen, but you can unlock a special cheat that allows you to multiply the drop rate of the various command chips dropped by enemies in exchange for lowering your maximum HP, up to 16 times its normal rate. The difficulty level of the game also affects enemy drops. A few of the game's strongest enemies will drop stat-boosting chips on Critical mode, the highest difficulty.
 * Suikoden II has this with the upgraded forms of Fire (Rage) and Lightning (Thunder) Runes. If you wanted more than one you could freely attach (and you did, as they were useful in many ways), you had to hope for a drop from specific enemies near the endgame.
 * Suidoken did it before, but much worse, as the best armor and accessories are Rare Random Drops too.
 * The Seeker of the Deep Expansion Pack of Lost Odyssey included some ridiculously good, ridiculously hard to get randomly dropped accessories.
 * This happens in Live a Live, with the Cola Bottle, a powerful accessory and attack item. It is a rare drop from a Guide Dang It Bonus Boss, which means that it is quite possible for the player to not realize that the aforementioned boss can even DROP a different item to its normal drop.
 * Raidou Kuzunoha VS King Abaddon features Ukemochi liver, a useless item that's necessary for exactly one sidequest, which in turn is necessary for One Hundred Percent Completion. The only way you can get it is by donating money to a shrine, at 300 yen a pop, for a roughly 1/256 chance of getting it. Cue an hour and a half of standing there throwing money at the shrine hoping to get it.
 * In the Etrian Odyssey series, you get raw materials from the enemy corpses, which you can then sell back to the local shops both for cash and to help create even better weapons, armor and other supplies. However, monsters don't always leave things behind, and many monsters also have Conditional Drops, which require you to meet certain conditions to trigger, like defeating it in a single turn or finishing it off with a certain element/status effect. Even if you meet the conditions, they still don't always drop, unless it's a boss... and many times, getting a boss to drop their special item also blocks the regular drop.
 * The third game, The Drowned City, has an NPC who frequents the local bar called Scavenger Toma. His whole purpose is to tell players how to meet most of these conditions, all for the low-low price of a drink or two.
 * Mega Man X Command Mission wasn't too bad about random drops, but one standout instance was if you were going for X's X Buster Mk-III or Zero's Z-Rapier+, both of which only had a 1% drop rate from one enemy in the final dungeon. You could boost those odds with Good Luck Force Metal, which increased item drops by 3% for each one equipped, but getting more than one of those required finding a specific enemy and beating it for the items to make it.
 * Although not an item, recruiting a Metal Slime or its family members in Dragon Quest V is hard. For the first one you recruit, you have a 1/256 chance of recruiting it and a 1/1054 chance of recruiting a second and third. Considering how tough they are once they reach their cap, that's fair. However, keep in mind that they are hard to find. The ordinary Metal Slime isn't too hard to find (they appear commonly in Whealbrook Cavern), but the Liquid Metal Slimes are very rare and typically appear with a bunch of Metal Slimes or other recruitable monsters, meaning if you get a crit on another recruitable monster after you killed the Liquid Metal Slime, you won't be able to recruit a Liquid Metal Slime for that battle. Fortunately, they aren't required, but they are very helpful against the bonus boss.

Turn Based Strategy

 * Final Fantasy Tactics A2 murders you thanks to this trope. What you can buy is determined by what pieces of loot you bring to the Bazaar, which is determined solely by how much of a lucky bastard you are. This means that it's almost impossible to tune your team to your liking until much, much further into the game, since most classes require that you have enough abilities in others to unlock them... and abilities are granted by these same items you depend on luck for finding. So you end up having to get by with whatever you have available.
 * Or by looking at the guaranteed loot given for completing a mission.
 * Eternal Eyes has many different items available as drops, but one of the most valuable is Magical Puppets; they're the raw material for your Mons, and each one you get equals a new unit. All monsters can drop them, but the chance is very low, and if you don't waste a turn opening the treasure chest it's in (no way to tell until you open it, of course), it stands a good chance of being destroyed by one of its former allies. A few chapter ends will simply give you a new puppet, so you will gain new units if you progress through the story normally, but if you want to expand your army further? Get to grindin'!

Web Comics
"Torg: "I've been putzing around for hours beating little salamanders to death with a stick in the hopes of getting a tongue out of them. And it's annoying because apparently not too many of them actually have tongues.""
 * Parodied in Sluggy Freelance when Torg plays an MMORPG and is beyond frustrated with his first quest.


 * In Cheer, Alex and Lita get trapped in an MMORPG world (thinking that they're dreaming) and are asked to get a Rat Tail that is "dropped" from rats. Lita, who has played the game on her computer, tries to get the item drop through the normal methods. Alex, who has not, gets tired of waiting for the "drop" and just uses her newfound magic powers to remove the tail from a dead rat.

Web Original

 * Neopets:
 * Random Drops can occur whenever you load a page. However, there exists a wide variety of these Random Events, which have many more effects than just giving you a rare item.
 * There are certain avatars that can only have a chance of being given when you perform a certain event. Some of these events can only happen once every 24 real-time hours. Coupled that these avatars are infrequent in distribution, it makes avatar-getters frustrated in collecting them all.

Real Life

 * Sweepstakes where prizes are won by collecting a specific set of game pieces—for example, McDonald's Monopoly or Subway's Scrabble games. One of the pieces in each set is rare: the amount of those pieces are equal to the amount of prizes available for that set. The other pieces are common, so you are enticed to keep playing the game to find the rare piece. The rules usually list the odds of winning the prize, which is also the odds of a given game piece being the rare piece for that set.
 * It's easy figuring out which letter is the rare to win which prize - just look for a letter that occurs ONCE in a given prize's name and doesn't occur in any other prize names. If you live in french Canada where the contests runs in english AND french, then the SAME rare letter much fulfill both conditions in TWO languages. Fun time being the guy who has to figure how to prevent the game from being Unwinnable By Mistake while simultaneously avoiding to give out half a million cars.