A guy's walking down the strip in Las Vegas when another man approaches him, asking for money because his wife is in the hospital and really needs an operation.
The first man thinks for a second and then asks, "I'd like to help you out, but how do I know you won't take my money, go into the casino, and blow it all at the roulette table?"
The second man answers, "Oh, you don't have to worry about that. I've got gambling money."
Note: I don't know who wrote this joke, but if I did, I'd certainly give them credit.