When 11-year-old Billy (LUKE BENWARD) arrives at a new school, he feels intimidated by the notorious bully Joe (ADAM HICKS). Wanting to fit in, Billy takes Joe's bet, that he can't eat 10 worms in one day without throwing up, even though Billy is prone to vomit at the slightest provocation, like watching the dryer spin or seeing his little brother Woody (TY PANITZ) drool. Billy is jealous that Woody seems able to fit in right away; his performance as a "sea turtle" with his kindergarten classmates has their mom (KIMBERLY WILLIAMS-PAISLEY) and dad (TOM CAVANAUGH) cheering him on.
At the same time, Billy's father is trying to adjust to his new office, so their efforts to seem "normal" run on parallel courses. Thus, as Billy spends Saturday trying to eat the worms and look after Woody, their mom and dad play tennis with his new colleague and his wife, worried about making a good impression. A third parallel is established in Joe's relationship with his bully of a big brother, Nigel (NICK KRAUSE), who taunts him, suggesting that Joe learned to be mean at home.
Billy's worm-eating efforts are monitored by Joe and his "team," including Bradley (PHILIP DANIEL BOLDEN) as the Official Timekeeper, Benjy (RYAN MALGARNI) as the Worm Cook, and Donny the Brain (ALEXANDER AGATE). Billy's moral support comes in the form of adorably dweeby Adam (AUSTIN ROGERS) and especially Erika (HALLIE KATE EISENBERG), who encourages him to keep up his nerve and so, perhaps, win respect and take down Joe a notch.
As the kids await Billy's "barfing," he is surprisingly able to keep the worms down, and grows more self-confident with each new worm recipe.