1 definition by Yourwordinformer

Top Definition
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. If you refuse to participate, you will arrested. Hence the "mandatory".
Markus: Yo dude, how was that party you went to yesterday?

Ken: Dude, it turned out to be a mandatory sex party!

Markus: Oooohh! Dude you got BURNED! HAH! So did anyone get arrested?

Duncan: WTH!?!?!?! Those are real?!?!

Allie: Told ya so!
by Yourwordinformer January 24, 2011
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