Jason has "the second biggest mouth in Mrs. Jewls' class" (12.1), which is pretty impressive because "there were an awful lot of big mouths in that class" (12.1).
Jason uses his big mouth to tattle on his classmates, and he tells Mrs. Jewls that Joy is chewing gum. (FYI: Joy has the biggest mouth in class, but she fills it with gum.)
Jason volunteers to write Joy's name on the board, and when he gets up she sticks her giant wad of gum on his chair. This glues Jason to his seat. Mrs. Jewls orders Joy to go home on the kindergarten bus—but that doesn't help Jason, who's still stuck to the chair. "I'm going to have to stay here for the rest of my life!" (12.12) he says.
The three Erics try to pull Jason free, but that doesn't work. Mrs. Jewls offers to go get some ice water from the lunch teacher, Miss Mush. Miss Mush's cooking skills are terrifying, but Mrs. Jewls reassures Jason that her ice water will be "at least as cold as her soups" (12.25).
Rondi and Allison tickle Jason when Mrs. Jewls leaves the room, and he laughs so hard that his hair turns purple. When Mrs. Jewls comes back with a bucket of ice water, she dumps it all over Jason. It doesn't help unstick him, though, so now he's wet and stuck.
Mrs. Jewls suggests cutting Jason's pants off, but Jason's really not fond of this idea. The three Erics pick Jason up and turn him upside down. He tries arguing that he's much better off permanently stuck to his seat—"Now I'll always have a place to sit down," he says. "I won't have to worry about finding a seat on the bus" (12.42).
Joy offers to free Jason on the condition that if she succeeds, she doesn't have to go home on the kindergarten bus. Mrs. Jewls agrees.
Joy kisses Jason on the nose, and Jason falls out of his chair.
Todd moans that now he'll have to go home alone on the kindergarten bus.