A homeless man walks into a bar and says "Bartender! Give everyone a round on me, and pour one for yourself!"
So the bartender does just that, and says to the homless man "That'll be 50 bucks."
"Well I dont have that kind of money," says the homeless guy. So the bartender throws him out.
A couple of minutes later the homeless guy comes back in and says "Bartender give everyone a round on me!"
"What, no drink for me this time?" the bartender replies smugly.
To which the bum replies, "Hell no, you're an asshole when you drink!"