A capacity crowd of 189 people attended the event at the adult-themed Oasis Aqua Lounge while more than 100 others stood outside trying to get in, the Toronto Star reported Tuesday.
As couples made out discreetly in one room, scattered baskets of condoms and lube were among the sightings that set the event apart from most university parties.
Some students ordered food, played twister and watched adult films.
Beginning at 7 p.m., nudity was allowed.
"People have been looking forward to 7 o'clock when clothing is optional," said attendee Cassandra. "I think it's more of a novelty than anything else."
She said extra rules put in place for the event, requiring student identification or being the plus-one of a student, made her feel more comfortable than she had expected.
"It's clear that it's not an orgy," said Dylan Tower, outreach coordinator for sponsor, the University of Toronto Sexual Education Center.
"The best way I can put it, it's a very sex-positive club night," Tower said.