Annoyed by Francine's attitude, Muffy bets that she cannot be nice for a week. Noticing how straining the bet is on Francine, Arthur, Buster, and the Brain try to get her to lose her temper, but Francine manages to keep it under control until the bet is over. When Arthur and Buster have to eat lunch with Binky's gang, the Tough Customers, they tell Arthur they think he has never "gleeped" anything, but to impress them, he tells them he has, only to find out later that "gleep" is slang for "steal." Rumors spread about Arthur being a thief, while Binky's gang pressures him into their ranks.