I think we have a winner. Although, unless the guy is bat shit retarded he probably won't try to rip off the same person again, so if he sees the OP he'll probably just bail.
fight him, nugget!
dont be a bitch and let him keep your 40 bucks. just get 4 of your biggest friends (preferably black) and fucking stomp his ass. after that take his wallet and run. its quite fail-proof... unless you get caught. he deserves it. and if you are too big of a pussy to get your money back then you deserve to be played.
don't be a pussy and bring the cops into this, he needs to know whos da boss so go buy yourself a gun and threaten the shit outta this mofucka like a straight thuggg