If you play Texas Hold 'Em for any amount of time you will eventually run into a poker maniac. All poker players know what a maniac is. He is a player so over aggressive as to be ludicrous. If you check, he raises. If you raise, he re-raises. If you raise strong, he goes all in. The one time he checks, he has a monster hand (or a complete bluff) and re-raises heavy after everyone else gets suckered into the pot.