Meet the Incompetent Player of Poker
This person doesn't take poker seriously (eegads!). Pot odds? What are those? He just wanted to get out of his house and drink a couple of cold ones with the boys. He's probably the guy who's not paying attention when it's his turn to act. You dread when it's his turn to deal because it's slow. He doesn't know how much the bet is when it's his turn to call. This guy can really put a table on the edge.
Expect erratic play. The incompetent will play less his own style (he doesn't have one yet) and more the styles that he's seen at the table.
What to do: Be patient with this guy. It's funny or not so much to his opponent how lesser players often win by flipping coins all night and hitting on ridiculous odds. Just have faith that all the poker-reading and odds-calculating that you do is worth something. Be patient and wait for him to make a mistake, he will because most of his play is a mistake. You just have to wait until you've got the goods and can massage all his chips right into your stack. Do some moderate slow-playing with good value bets, and try to isolate him in the hand so you two as heads-up. Continue stroking.
In a No-Limit game: Due to his inexperience, this guy will raise on a weak hand pre-flop. Be careful that he isn't too excited or feigning interest altogether, as these may be signs that he actually has something. Wait until you have a decent hand and re-raise him pre-flop. If you still think you have him beat after the flop, just gently massage his chips to your side of the table. Value bets of about two or three times the Big Blinds will keep him in and keep him paying.
In a Limit game: You'll have to re-raise him pre-flop. Depending on your position, either re-raise if you're after him or check-raise if you're before this guy. The check-raise is useful here to literally make him think twice about his hand after the flop. Follow the same strategy for the turn and river, make his inexperience expensive.
Example: You: K-Q, Incompetent: Q-6. The flop comes A-7-T. You have to raise and re-raise here to make him think about the hand, since you're figuring you're still ahead, bet half the pot in No Limit or check-raise in Limit. It's still yours for the taking.