Audiences LOVE to see a magician pick the pocket of an audience helper, and you can add this very funny bit to your act in one of two ways.  One, you can practice like crazy until you can really pick your spectator's pocket.  Or two, you can use Tom Burgoon's Power Pickpocket gimmick.  

Get the spectator on stage, and after "positioning" him, gently moving him to a specific standing spot, you turn away, apparently holding his wallet.  Open it, take out a couple bills and then turn back to him, saying you need him to stand "over there a little more".  Again you gently help him to his place, and (apparently) replace his wallet.     Or you can simply reach behind your spectator and then hold up a wallet, open it, look inside, even take out a couple bills, and then apparently put the wallet back.

Made in very high quality by Magic by Gosh -- that's a clue as to how this idea works -- Not really meant as an earth-shattering mystery, but it is VERY funny.   The sponge wallet is not very realistic looking under close scrutiny, but at typical stand-up show distance, it passes.  And also because the act of pick-pocketing is inherently furtive, it is natural to be somewhat secretive when the wallet is pulled from the spectator's pocket.  So the audience never gets that good a look.