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1.
When saying this phrase make sure you have either a shotgun or exploding device in your hand before using it on someone who doesn't expect it.
(Playing Call of Duty Modern Warfare 2)
IndianaPWNS-(Has RPG in hand) ooo Sup BRO

KillerInstinct-(C4)dude I just sup broed that guy
Mr. Bubbles-(Spas12 turns the corner) SUPPPPPPPPP BUHBUHBHUBUHBROOOOOOOOOOOOOOOO
by Nareik Kciradorb April 02, 2010
 
2.
N. Someone like a surfer or cocky person who likes to start sentences with Sup bro? (whats going on brother) so often it's ridiculous
N. THe male version of a valley girl
kate: oh my don't pop your collar what are you some frat boy sup bro ?
zach: your an ass
by PB SLAPPER June 24, 2010