"For Sure"... White version of "Fo Shizzle" or "Fo Sho"
-Can I have a bite of your cheese sandwich?
-Fo Shagenoff, my white brethren
Can mean anything you want it to. It can be used to replace words that you would get in trouble for.
Stop touching your treenie and get your treenie outside you fucking treenberg. (cock, ass, dipshit)