First you draw up some tears, you beg him to let you live. Turn and give him some sad puppy dog eyes. By now he should be pretty aggraveted that your more scared then cooperative. This is when you tell him the wallet is on the side where he has the gun held. If your lucky he'll switch the gun to the other hand, and you have a chance to knock it out of his hand with a simple slap then you can show him yours. If your not lucky he'll use the other hand to get the wallet, so you can grab down on the gun and point it away from, and you kick him in the nuts. If all else fails....tell him you know Chuck Norris.
Every day above ground is a beautiful day.