South Park: Season 4, Episode 8

4 - 8: Something You Can Do with Your Finger (a.k.a. Fingerbang)

Cartman and the boys put together a boy band called "Fingerbang." When Stan's dad hears about the musical group, he tries to prevent Stan from being a part of it. As Stan tries to figure out why his dad is acting so strangely, the rest of the guys wait for him at the mall where they're late for their first gig.