The ice hockey player, who will marry the country singer on 10 July (10), invited 15 close male friends to join him at the city's Mansion nightclub, where they guzzled booze and danced on tables.
The boys proved they knew how to party - and the fun and games took a bizarre turn when one of Fisher's pals tried to relieve himself in an office.
A source tells the New York Post, "Fisher nursed a couple of cocktails throughout the night and watched the debauchery from a sofa. They were dancing on the tables and handing out shots to girls.
"One of his friends attempted to urinate in an office next to the bathroom, while another drunkenly asked the waitress if she'd be his date to the wedding."