(You) wanna step outside?

(You) wanna step outside?

Do you want to get into a fight with me? Will we go outside to settle this with a fistfight? ("Wanna" is a colloquial contraction of "want to.") What are you looking at, punk? Wanna step outside? A: "You're a stupid jerk, and your mother sucks eggs!" B: "Oh, is that right? You wanna step outside, you little weasel?"
See also: step, wanna