Tell him to side arm it a few degrees more and/or keep his rod on plane (thumb strait at the target); his tip is undoubtedly following an oval path if he's whacking himself. Oh yea, remind him to wear a hat and sunglasses when he starts throwing streamers.
Obviously, he is thinking like a fisherman. Let him color up anything he wants. Have him start hitting some targets if he wants to catch fish, though.
Alternatively take him to a casting competition. Might be the next Steve Rajeff.