When you and someone else are in an argument, and the other person says they are better than you (scored more goals in a game, got a better grade, etc.) and you tell them you got the better grade or what not, adding on the end, "sup dude?" in a nonchalant manner, just to rub it in.
Jake- "Hey man, how'd you do on the test last week?"
Mike- "I got a 95, how'd you do?"
Jake- "I got a 98, sup dude?"