do not pelt him with tacos to exact your revenge. He will merely consume them like the insatiable fiend that he is.
Do not lend him money. He uses other people's credit cards to pay his electricity bill. Do not give him a ride anywhere--let him walk. His car was impounded. If he gives you a story about being on disability don't believe him. He's not sick. He's an asshole.
I know it's hard, but do not to help him. Pac-Man will do you wrong everytime.