I'm going to steal the money jar from a homeless guy while he's sleeping
Why would you steal from the homeless?
It's so easy to do something that doesn't require any effort. And it might be fun too.
You're being really cruel to that homeless man. It's his money and he needs it so it's not right to steal it just for fun.
If he's stupid enough to have a money jar out in public than he deserves to get robbed.
I don't think that he has anywhere else to put it though. You should just leave him alone, it could be the only money that they have to their name.