While Mr. DeFazio is away for a few days, Laverne and Shirley take over running the Pizza Bowl for him. Later, The Fonz convinces the girls to let him host a wild bachelor party at the Pizza Bowl - it goes against Shirley's better judgement, but Laverne doesn't see any problem with it. When the party gets started, however, the girls both begin to realize just how much of a mess they've gotten themselves into.

The girls get engaged to Richie and Fonzie to avoid a shotgun wedding.

The crossover starts on Happy Days S07E01 Shotgun Wedding (I).