According to Jim

Cheryl forbids Jim from throwing his cop friend Danny a bachelor party with beer and strippers. She fears that Danny will show up at his own wedding with a hangover – as Jim did at their wedding. Jim and his buddies decide to take Danny for a swim in bitter-cold Lake Michigan – forcing a hospital visit for Danny. The wedding morning, Danny stays in bed, moaning and groaning, and Cheryl frets, but the doctor assures everyone there's nothing wrong with him. Jim realizes Danny just has cold feet, so he tries to convince him to go through with his wedding to Laraine, a fellow cop.