Mattress Jousting

Yes, it is a game played in college frat parties but has nothing to do with actual jousting. It is the act of two male parteners who are clearly intoxicated partaking in the act of sword fighting (this is where the jousting comes from) with their wangs on a bed (mattress).

It is commonly used as a joke to people who are clearly uninformed about the slang term.

Frat boy: Hey, Jason, do you want to go mattress jousting later on tonight?
Jason: No, I'm not gay
Frat Boy: I am

John's Older Brother: Hey John have you ever gone mattress jousting?
John trying to be cool: Yeah me and steve mattress joust all the time its fun as hell
Steve: I always win
(Arguing over who wins when both are now labeled queers
John's older brother: Wow?