In the Discworld novel Unseen Academicals, Mr. Nutt comes Back from the Dead, feeling hungry, and eats nine pies. He's a pretty small chap, and, anyway, nine pies, and as such, is described as looking like a snake that swallowed a goat.
In The Dresden Files, Harry pays his "spies" (fairies) in pizza. After they've violently consumed the pizza they look like this, but they return to their normal shape after a few minutes.
Harry Potter and the Prisoner of Azkaban has Marge Dursley being blown up like a balloon for saying that Harry's parents "died in a car crash". In Order of the Phoenix, Harry eats enough at Grimmauld Place that his jeans which had once belonged to his obese cousin Dudley felt snug (courtesy of master chef Mrs. Weasley).
In Antoine de Saint-Exupéry's The Little Prince (and its movie version) the aviator draws a boa constrictor with an elephant inside. Since the back of the snake is the one he draws as distended, it gets mistaken for the drawing of a hat the first time he shows it to other people.
In Lois McMaster Bujold's Mirror Dance, Miles Vorkosigan's clone brother Mark binges on combat rations for two weeks, bringing his weight up too in a half-conscious effort to separate himself from his progenitor. Which looked alarming enough given they both are under five feet tall. And then it goes From Bad to Worse.
A verse by Shel Silverstein: "If I eat one more piece of pie, I'll die! If I can't have one more piece of pie, I'll die! So since it's all decided I must die, I might as well have one more piece of pie. MMMM—OOOOH—MY! Chomp—Gulp—'Bye."
Children classic Winnie-the-Pooh does this. Pooh eats so much he gets stuck in Rabbit's burrow.
Noncomedic example: According to the Zombie Survival Guide, since zombies don't digest human flesh, they can end up with distended stomachs fairly quickly.
Poor Stuffy Pete ends up with one after guilt-tripping himself into eating two huge Thanksgiving dinners in succession by mutually unaware benefactors in O. Henry's "Two Thanksgiving Day Gentlemen".
In Charlotte's Web, when Templeton the Rat returns from stuffing himself on the bountiful discarded junk food at the county fair, the author describes him as "big around as a jelly jar", and by the end of the book, he gets even bigger as a result of Wilbur keeping his promise to let him have first dibs when Lurvy puts out his food.