Speak Friend and Enter

Frodo: It's a riddle. "Speak friend and enter." What's the Elvish word for friend?

Gandalf: Mellon. (door opens)

—The Lord of the Rings: The Fellowship of the Ring (film adaptation)

Gandalf: Gandalf, you old fool. Mellon! (door opens)

Legolas: So all you had to do was speak "Friend" and enter.

—The Lord of the Rings (animated adaption)

In any story, there are problems. Characters need to solve those problems. Usually, they do so in the most straightforward way. But sometimes, they create an extremely complex and convoluted plan for what should be a simple solution. They may just plan it, or they may actually go through with it, but often before, during, or after, some other character points out how complicated the plan is, or what the simplest solution would be.

Compare with Zany Scheme, which is what happens in a Sitcom when people go through with a complicated scheme (and often, either no one knows or realizes that there was a simpler solution, or there wasn't one).

Compare with There Was a Door, a specific subtrope where rather than simply opening a door, someone smashes through the door or wall (though actually, smashing through is simpler in the short term, and only in the long term is it more complicated). Also compare Cutting the Knot. May overlap with We Have the Keys if the "key" is found before the more violent solution is tried (or after the more violent solution has failed).

Examples of Speak Friend and Enter include:

Anime & Manga

In Ranma One Half, Ranma gets a cursed spatula attached to his hand (don't ask). It will only come off when it is "used properly". Every attempt to use it to cook results in disaster and magic energy bolts flying all over the place. Then someone realizes that the Japanese phrases "use properly" and "use fish flakes" sound identical. They sprinkle on some fish flakes and the spatula falls right off.
Pokémon uses a variant of this trope, amazingly enough, in the second movie: "And the world will turn to Ash."
In Working!!, there's a brief subplot where Inami tells everyone at Wagnaria that she mentioned she had a friend named Takanashi to her mother, who mentioned it to her father. Her father doesn't want her to have any male friends, so Inami begs Takanashi to cover up for it by crossdressing. Only after he's reluctantly agreed to do it does Yachiyo point out that they could have just had a girl like her pretend to be Takanashi when her father came to meet him. Souma thought of it, but didn't feel like bringing it up. Because it's funnier that way.

Comic Strips

Robotman and Monty: After a week-long story in the comic strip where Monty thinks he locked himself out and tries all sorts of ways to coerce his cat to give him the keys (the cat gives him peas) or get the keys himself, he eventually gets stuck in the cat door. His friend Moondog walks up to him, and when Monty asks how he got inside, Moondog says the front door was open.

Fan Works

In With Strings Attached, the Hunter, with twenty years of nonstop adventure behind him, begins to plot out a long, difficult slog into the Misery Mountains, citing lurking undead and other nasty things lying in wait along the cold, windy, miles-long path. George stops him and basically says, “Hey, I'll just turn into a dragon and fly us up there.” End of problem.

Films -- Animation

The Disney version of The Hunchback of Notre Dame: Quasimodo and Phoebus find the entrance to the Hall of Miracles (the Gypsies' secret hideout) using the amulet Esmeralda gave Quasimodo. The amulet leads them to a large grave with mysterious writing on the lid. While Phoebus tries to decipher the writing, Quasi simply lifts it open, uncovering a staircase.

Films -- Live-Action

Bedknobs and Broomsticks: Near the end, they realize the spell they were looking for was in the child's book all along. This make a large part of the movie somewhat of a Shaggy Dog Story in retrospect.
In The Bourne Identity, Jason and Marie are trying to obtain some information from a hotel's files. Jason comes up with an absurdly complicated scheme for acquiring this information, and instructs Marie at length about the precise timing and attention to detail required before sending her in. She returns thirty seconds later, having decided to simply walk up and ask the clerk for the files after claiming to be Bourne's personal assistant.
Terminator 2: Judgment Day. Dyson outlines the complicated method of opening the glass cabinet containing the original Terminator chip. John Connor just smashes it.

Literature

In The Fellowship of the Ring, Gandalf spends hours casting opening spells and trying passwords on the door into Moria. He finally realizes that he mistranslated the inscription on the door: instead of "Speak, friend, and enter", it was "Say 'friend' and enter" All he had to do was say the elven word for "friend" and the door opened. Gandalf read the inscription aloud before, but in the common tongue, not in Elvish.
In the parody Bored of the Rings, Goodgulf tries many passwords before realizing that the door has a knob.
Muse magazine's Affectionate Parody of The Lord of the Rings had the inscription on the door read, "I give up my secret". Naturally, the door opens when the "Gandalf" character (played by Chad) exhausts all his ideas and says, "I give up!"

Live-Action TV

In the Red Dwarf episode "Rimmerworld":

Lister: Why don't we scrape away this mortar here, slide one of these bricks out, then using a rope weaved from strands of this hessian, rig up a kind of a pulley system so that when a guard comes in, using it as a trip wire, gets laid out, and we put Rimmer in the guard's uniform, he leads us out, we steal some swords, and fight our way back to the bug.
Kryten: Or we could use the teleporter.

Head of the Class: Dr. Samuels gives the class an assignment: how do you measure the height of a building using a barometer? After several explanations, he asks the new sub Mr. Moore how he would do it.

Mr. Moore: I'd say to the super, "if you tell me how tall this building is I'll give you this neat barometer."

- This is a reference to a tale of similar smartassery on the part of Niels Bohr (in his university days).
In the Sherlock episode The Blind Banker, John finds a wall covered in graffiti that's actually the code that will allow them to solve the case. He runs to fetch Sherlock, but by the time they get back, the entire thing's been painted over. Sherlock then spends the next minute or so pressing John to remember the code, waxing lyrical about the fallibilities of the average human mind's memory capacities, all the while ignoring John's protests and attempts to get to his camera phone, on which is stored a picture of the entire wall before it was painted over.

Radio

The Men from the Ministry: The protagonists are faced with an infestation of mice. One character suggests using high tech methods to get rid of them such as laser beams or ultrasonics. His secretary suggests a cat.

Tabletop Games

In the Paranoia adventure "Send in the Clones", the PC's encounter a door with a panel of buttons nearby. If they push the buttons and succeed in a difficult skill roll, the door opens. If the skill roll fails, the door stays closed. If they just push on the door, they find that it was open all along.
Dungeons & Dragons
- In module C2 "Ghost Tower of Inverness", the PC's get extra points if they enter the castle ruins by climbing through large holes in the wall rather than wasting time opening the gate.
- Module I7 "Baltron's Beacon" has a Shout-Out to The Lord of the Rings example. A door has the inscription "Sayez Chi, Passant Avantre" ("To pass through, say who"). If the party uses magic to read the inscription they may think they need to say "who" in Common: they actually need to say "Chi", which is the word for "who" in the language the message is written in.
- First rule of lockpicking: check that the locked door is actually locked. Although this rule isn't published in any Dungeons & Dragons product that we are aware of, this rule was learned from another D&D player while playing a rogue.
- [Brackets] once included a dungeon with a nine-letter tumbler puzzle locking a door, with the riddle question: "What is the mirror that shines in the darkness?" The answer was Moonlight. Moonlight is the mirror that shines The moon reflects light from the sun, thus making it a mirror.
Rolemaster Shadow World supplement Emer. Inside the Ahrenthrok, a door made of frosted green laen has a silver rune inlaid on it. It will open if the Iruaric word "I Ken" ("open") is spoken.

Video Games

Zork: Grand Inquisitor
- In Hades, the player is tasked with answering a bunch of questions on the Hades Hotline telephone before he/she can call a shuttle. It's made especially confusing (the Hotline strives for "customer dissatisfaction") by the fact that, for example to press 6, you need to press 2, and to press 4, you need to press 0. The puzzle is doable, and there are only 5 questions, but it can also all be overriden if the player casts "Kendall" to simplify the instructions.
- Another example presents a puzzle board with several moving pieces activating a lock that opens a small cage holding a skull that the player needs. The player simply smashes the cage open with a club to proceed.
Bureaucracy: this Interactive Fiction game, written by Douglas Adams, has a puzzle that consists of a locked door in an apartment complex. The way to get the door open is to do something no experienced adventure game player would ever think of trying, but someone faced with the same situation in Real Life would probably have no trouble finding the answer. Simply knock on the door, and the person inside lets you in. It's that kind of game.
In the third Metal Gear Solid, knocking on the door is also the solution, contrary to anything your support team suggests, to getting through a random locked door in the enemy base.
In Final Fantasy XIII, Lightning tries almost everything to get a certain door open. Then, for some reason, she gives the door a hug, and says: "I'm sorry. Please open." The door pops open, and every other door of that type opens without a fuss from then on. This happens because the doors are fal'Cie, and thus living creatures who don't respond well to being punched and knocked on.
Leather Goddesses of Phobos: The player is captured by aliens and thrown into a cell. The way to escape is simply to open the door -- it's not locked. Many players were stuck for weeks on this point. Lampshaded in-game as well—the other prisoner admits he never thought to try it.
In the Infocom game Journey, the characters find a gate with an inscription reading "Please only say 'gate open' to enter storage-room." Clues allow the player to read this correctly as "Storage-room entrance. To open gate, say only 'Please'."
In Knights of the Old Republic, to choose your Jedi class, you are asked a series of questions, one of them being "You are at a locked door. What do you do?" One of the choices is "knock".
In Battlefield: Bad Company 2, the squad captures a Russian soldier and intends to interrogate him for information. While The Sarge goes off to talk to him, the other soldiers start talking about how effective he is at torture and betting on how long it will take the guy to break. Sarge comes back in seconds, having simply asked the guy straight-up. Apparently, he was just a Russian conscript with family in Houston, and wanted no part of the whole thing.

Web Comics

Schlock Mercenary here.
Another case of a character locked outside in this this Xkcd strip, only geekier.
The Lord of the Rings is parodied in this strip of DM of the Rings.

Western Animation

In The Fairly OddParents, Timmy, Chester, and AJ are sent to a military school, where they are forced to conquer an obstacle course. One obstacle is a sixty-foot climbing wall covered in spikes. While Timmy and Chester are in awe of what they seemingly have to climb, AJ comes up with a simpler solution—walk around it.
Xiaolin Showdown: Clay does something similar to circumvent an obstacle course.
- To elaborate, there's this huge obstacle course covering the area that loops around to a pedestal with the goal. After the others have failed to get through the course, Clay asks if all he has to do is get the object at the goal. When told he does, he simply walks over to the pedestal and picks the goal up, completely ignoring the obstacle course.