Girls must be complete randoms and must be unaware of each others presence. Must be naked. No other circumstances apply.
Roommate #1 Fucks said slut
Roommate #2 brings unrelated slut from different game
Roommate #2 Fucks said unrelated slut
Slut #1 Walks out of Room Naked
Slut #2 Walks out of Room Naked
Both Sluts (mind you, unrelated), pause
Both Sluts return to respected roommates room.
Hence the Naked Hallway Collision NHC