The kind of sex that happens in a tight space; you can also have trouble breathing during this time. Places where you can have coffin sex include closets, small bathrooms, dressing rooms, etc.
A: I had coffin sex with my girlfriend the other night.
B: It must've been pretty tight, then. Where'd it happen?
A: In the bedroom closet at my parents' house.
by un-named August 30, 2006
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