syfsau

An abbreviation for the phrase "Shut yo(ur) fʊ##ing stupid a$$ up". Pronounced "sif-sou"

person 1: Shut up bro yo momma built like the great wall of china if it was all packed together my guy
person 2: Bro you deadass still using yo momma jokes like syfsau bro on god
person 3: Dang, you finna let that slide bro?
person 1: I might have to bro that one was a critical hit my guy