Hank encourages Bobby when he is asked to cheerleader for the girls in the school's annual Powder Puff game. Bobby soon learns that there is a tradition and Hank, Bill, Dale and Principal Moss were once "Powder Puff Boys" themselves. However, the boys learn that Peggy and the PTA Are trying to put a stop to the tradition.

Stressed that her birthday parties never live up to her expectations, Peggy plans herself a disco-themed party on a mystery train, but after Luanne ruins the surprise, Peggy worries her parties will always end badly. However, a new mystery arises after a couple sneaks away for some private time in the train bathroom, and the partygoers must figure out who did it.