Having kinky sex with strangers, freinds or groups in a hotel room during a Anime, Fantasy or Sci-Fi convention. Anime fans don't like to talk about Con Sex, but it happens all the time especially at the larger conventions. Some Anime fans come to cons just for the sex, the kinkier or weirder the better.
Cosplay is a big part of Con Sex, and S&M and Bukkake can easily happen during Con Sex orgies.
Did you hear about the Sailor Moon Con Sex orgy at DragonCon this year?