Bottom has a subtle (by its standards) use of this in the episode "Gas", when Eddie stands up after eating almost the entire contents of the neighboring flat's fridge. It's gone again a couple of shots later.
CSI: Crime Scene Investigation had a rather nasty version of this when a guy was trying to use a device designed to help with dressing deer carcasses and help another guy with something. The victim basically got inflated to death. (though it wasn't murder in that situation).
Likewise, NCIS did a serious version where an eco-terrorist tricked his way onto a Navy sub to release deadly gas there from a cold-triggered canister. When his first plan failed, his backup was to swallow the capsule of gas and commit suicide, so his body would be placed in the freezer and chill the capsule to the point of release. His body had a gas-swollen belly when the team found it, but fortunately remained intact long enough for the team to launch it from one of the torpedo tubes.
Over the course of the three-week Labor Day break, Jon Stewart has become so obese that special effects are required to make him look normal. John Oliver points out Stewart's obesity, but later "reveals" that he is a hallucination caused by Stewart's onset of diabetes.
"Why did I rent that ice cream truck...?"
In F Troop, Agarn acquires one at the end of "Survival of the Fittest".
In the commentary for an episode of Firefly, during a Shirtless Scene, Alan Tudyk wishes they hadn't shot right after he had a big lunch.
In The Goodies episode "Holidays", Bill drinks so much tea he ends up with a huge balloon belly, which stays with him until the commercial break.
Hannah Montana has Lily; Though normally she is a Big Eater, the only time she visibly gained weight was in "No Sugar, Sugar", where she ate an entire buffet made of nothing but sweets.
Lily: I spent the entire night devouring everything Oliver tried to look at! I've eaten my entire body weight in cupcakes alone!
At the beginning of the Honey, I Shrunk the Kids episode "Honey, It's Gloom and Doom", Wayne gets one after tasting the fizzy breakfast drink he invented. This happened because he put too much sugar in it.
Incredible Crew: In the episode Face Jeans, there was a sketch where Chanelle was at a spelling B and she got her word wrong. She gasped and inflated like a human balloon, quickly floating in the air as if filled with helium. And then, like a balloon, she cartoonishly started flying around the auditorium and her then deflated body fell to the floor.
Monty Python's Flying Circus has Barry Zeppelin, the least talented brother of Ferdinand von Zeppelin. After Barry fails to inflate a large balloon, the balloon inflates him.
The titular character of The New Adventures of Old Christine gained several pounds in the episode "He Ain't Heavy"; originally she had only gained weight in her butt, but eventually she gains enough weight for her stomach to start growing too. Both her belly and her butt remain swollen for the rest of the episode.
Sabrina: I think I might be retaining water. ...Or syrup.
This happens to Harvey in another episode, when he is captured by the witch from "Hansel and Gretel".
Amy Pohler used the balloon/pregnant belly gag on Saturday Night Live when she was having her first child, while still a cast member.
In the Small Wonder episode "Fat's Where It's At", Ted enabled Vicki to extract energy from food the way humans do. He also unwittingly gave her a superhuman appetite, which exceeded her digestive ability.
This happens in a Reality Show, of all places. Survivor's 20th season has Courtney Yates, who, after getting voted off and sent to Ponderosa, eats enough to make her stomach visibly bulge. She then goes to show it off to the camera:
Courtney: (pats belly) That's my food baby. ...Don't worry, I'm going to work out tomorrow.