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Pronounced Simbeefee. Acronym for "shut your mouth before I fuck it"

Short phrase you can use in public to tell your girlfriend to shut up in a vulgar way without offending people around you.

Used to silence someone with emphasis.
Girlfriend says, "Will you carry my purse?"

Answer. "Symbifi"
by heeg January 03, 2011
shut your mouth before i fuck it.
GUY1-im going to the club.
by 9deuce October 04, 2009