1.A basic rule in street fighting to gaurd against an attack from someone's right hand.

2.Euphemistically to take precaution against expected obstacles.
1. Yo son you wann eff w/ me he better keep your left up that's my word.

2. You making that run on the fourth? Yo, you betta keep your left up the feds be creeping!
by The Amalamps May 9, 2006
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