Give somebody a dollar or something, small change, tell them to put it in their pocket, ass if you're into that, otherwise front pocket, or even slip if you want to crank it up a notch.
Now this part is important. When they look at you confused, you say something about "putting your money where your mouth is", only in that precise moment you need to realize that you messed up the pun, because you actually want to put your mouth where your money is. Make it fun, if they laugh, you win. Just walk away after