Kill It Through Its Stomach

Bob is devoured by a monster. Monster looks pleased at its victory and goes to eat Alice. Alice is terrified until the monster stops, gives her an odd look, and screams as Bob cuts his way out of its stomach.

If Bob had yelled "Eat Me!" moments before, then he was almost certainly planning to do this, and obviously, it doesn't work unless said monster swallows people whole. Let that be a lesson to all you monsters out there: always chew your food properly.

See also Chest Burster, Just Eat Him, and Feed It a Bomb. Not to be confused with Through His Stomach.

Anime and Manga

 * In Rosario + Vampire, Moka is eaten by a plant monster. Inner Moka then literally kicks her way out of the monsters stomach.
 * Near the start of the Three By Three Eyes is a variation. Yakumo doesn't really have any powers yet, but manages to kill a monster (temporarily anyway) by shoving a summoning staff into its mouth and summoning Takuhi inside it to burst its stomach from within.
 * Naruto was once swallowed by a gigantic snake summoned by the Big Bad. He escaped by making so many clones of himself that it burst.
 * In Yu Yu Hakusho Three Kings Arc, Shishiwakamaru done this to a Giant Mook.

Comic Books

 * Multiple Man of the X-Men would do this by sticking his hand in an enemy's mouth and creating a bunch of duplicates of himself effectively bursting the person from the inside out.
 * Invoked in Nextwave, where the plan to defeat Fing Fang Foom involves Aaron Stack jumping into the monsters mouth specifically so he can cut it apart from the inside.
 * In the series Demon Knights, Etrigan climbs inside a dragon's mouth to cast a spell and make it explode from the inside.
 * In Frankenstein: Agent of S.H.A.D.E. Frankenstein is swallowed by a mountain sized monster. A page later he bursts out of it's body with his sword in one hand and it's heart in the other. The "why didn't it chew him" factor is justified here as the creature is so gargantuan Frankenstein's not much more than a crumb to it.
 * Zogonia in Dragon magazine had a variation: the party's thief Kev was turned into a frog by a lich. So he jumped at the lich's face and crawled into eyesocket. After that, Kev ruined every attempt at  spellcasting by emitting a loud croak inside the lich's skull and passed the rest of time sharing his  comments on everything else the lich did and complaining about how gross a place it is, until his team's leader clobbered the lich.

Film - Animated

 * Hercules defeats the hydra this way in the Disney adaptation of the legend. Unfortunately, it comes back to life with three more heads...
 * The dragon scene from The Pagemaster. After Richard is eaten by a dragon, he makes a beanstalk appear by opening a book entitled Jack and the Beanstalk that was also inside the dragon's stomach, and uses it to escape.

Film - Live-Action

 * In the Hellboy movie, HB kills the monster at the end by letting the monster grab him, and yanking the pins out of an entire belt of grenades just before the monster swallowed.
 * K in Men in Black does this when he talks the giant alien cockroach -- who had earlier eaten both his and J's guns -- into swallowing him whole. His explanation to J prior to doing this was "I'm goin' to get my gun back." He does, and proceeds to blast said giant alien cockroach in two from the inside out.
 * The alien assassin from Men in Black II is tricked into flying down Jeff the giant worm-creature's gullet, but grows large enough to burst out of him for a final battle with J.
 * The post-credits stinger to Pacific Rim shows Hannibal Chau cutting his way out of the baby kaijuu's gut.

Literature

 * Tobias and Rachel are swallowed whole by a Kronosaur in Megamorphs #2. Rachel proceeds to use her grizzly bear morph to rip her way out.

Live-Action TV

 * Piper and Grams from Charmed were once eaten by the Big Bad Wolf. Piper uses her power to blow the fairy tale beast to smithereens while she was still inside of it.
 * Earlier in the series Piper's plan to defeat a demon was to let it eat her and her sisters and then Prue would use her powers to blow it up. Fortunately, they didn't have to do it this way.
 * While it's unclear whether Buffy was actually ingested by the monster, in one episode she defeats this mother of body snatching beasts by slicing it with a pickaxe, presumably from the inside out.

Mythology

 * In the Golden Legend, this is how Saint Margaret of Antioch survived her first martyrdom phase. She was to be eaten alive by a huge snake (for some, Satan in the form of a dragon), but her cross pendant irritated the dragon/snake's innards and it bursted open, with an unharmed Margaret popping out of it.

Tabletop Games

 * In Dungeons and Dragons, PCs that get eaten by the tarrasque sometimes have to cut their way out. Sometimes it's actually a good idea, as its stomach does less damage than its outside.
 * This was completely and hilariously averted in 3.0 and 3.5, where any number of things (Tyrannosaurs, giant sharks, purple worms) could swallow you whole, requiring you to cut your way out... but slicing a giant hole in the critter didn't deal any actual damage to it, and "Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out."

Video Games

 * This is doable by your PC in Nethack and is in fact the safest way to kill some of the bosses.
 * Kratos does this to Cronos in God of War 3 in probably the mother of all Colossus Climb battles.
 * During one boss fight in Yoshi's Island, Yoshi and Baby Mario are shrunk and eaten by a frog. You then "defeat" the frog from within its stomach by throwing eggs at a uvula-like appendage.
 * Halfway through the first boss fight in The New Zealand Story, the ice whale you're fighting swallows you. You have to shoot it while avoiding the drops of acid in order to destroy it from within.
 * In Muramasa the Demon Blade, Momohime convinces the Big Oni to swallow her whole, which lets her start fighting it from inside its stomach. That doesn't necessarily discourage it from swallowing her again.
 * In Tales of Legendia, the largest monsters in the game are too big for Senel to throw, so instead of throwing them, he'll invoke the trope by jumping into their mouths and pummeling them from the inside while they're dazed from being knocked down.

Web Comics

 * Red Mage does this to a dragon in Eight Bit Theater using frost magic. Interestingly the dragon was only acting in self defence and was perfectly happy to help the remaining Light Warriors when they didn't attack. Indeed RM killed him half way through making them some fireproof armour.
 * Later, he defeated Kraken this way, bisecting him from the inside with his sword.
 * In Chirault, Kiran gets swallowed by a demon, then hacks his way out with his Blade on a Stick.
 * In Order of the Stick, V gets eaten by a dragon, and uses a Shapechange spell to burst his way out.

Western Animation

 * Adventure Time: Finn must slash his way out of the gullet of a… something, after Marceline tells him, "Use my axe bass."
 * Duck Dodgers employs a non-lethal version of this trope, Played for Laughs naturally. Daffy, unable to beat the enemy (played by Taz), decides the best answer is cooking himself, then serving himself up to his foe explicitly saying "Eat me!" After this, he proceeds to stand up fully inside Taz's stomach. Complete with obligatory Lampshade Hanging, but not in the usual manner. See the scene in it's entirety here.
 * In the Planet Hulk animated film, the angry green giant himself jumps into the flaming mechanical jaws of a robot worm only to pop out minutes later though its chest tearing out, what could be assumed to be, its intestines with it.

Real Life

 * A toad was once poisoned to death after swallowing a poisonous salamander, who then proceeds to climb out of its mouth.
 * A poisonous cane toad was once swallowed whole by an over-eager dog who thought it was a pastry. Both survived, though.