The Boston Sea Crab is when a man ejaculates in a woman's anal cavity and the female farts and it comes back out
Gary - "Oh I am about to nut"
Shirley "Not in my ass!"
Gary "OH MY GOD"
Shirley "You came in my ass"
**Shirley Farts and jizz comes out**
Gary "I just gave you the Boston SeaCrab"
by Nee Nee Boy October 23, 2007
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