markus: yo dude, how was that party you went to yesterday?  ken: dude, it turned out to be a mandatory sex party
"when someone invites you to a birthday/frat/whatever-other- kind-of-party-you-can-think-of party and it turns out to be a sex party
"markus: yo dude, how was that party you went to yesterday?  ken: dude, it turned out to be a mandatory sex party" What is the definition of "mandatory sex party"?