Helping someone who just doesn't get it

I've been running a NL Holdem tournement for some coworkers for a couple of months now. The level of play varies greatly, but overall people have a good time and have picked up the game quickly.

However, there is one guy who comes to many the games who still doesn't know how to play and needs to be helped along constantly. It was fine the first time, since he had never played before, but now after 4+ tournaments he still tries to check when it's been bet to him - "Can I check here?" "No, the bet is $200 to you", or will muck his cards on the big blind in an unraised pot, or will ask "Can I bet now?" when it's been checked around to him. It's been frustrating a lot of the players because they keep having to hold his hand through the whole tournament. And then he puts everyone on tilt because he gets a monster hand and doesn't even realize it: "I have two pair." "No, you have a full house."

The last tournament, the other players gave him a hard time constantly and it was very distracting for everyone. So my question is... what can you do for someone who just doesn't seem to understand the flow of the game? What can you say to someone to try to get them to pay more attention? He likes playing and isn't going to stop coming, but he is really slowing the game down, almost to the point of keeping some people from coming.

Thanks.