hmmmm... first thing that came to mind for a fun-loving, oddball intelligent guy is something my ex-boyfriend (same desciption as your friend) loved... mind games & puzzles. You know the ones, like a stick on a rope and you have to figure out how to make the rope separate from the stick? Or the ones where you have different shapes and have to figure out how they piece together to fit into a square? I know some of those come in colors, because my ex-boyrfiend had them! LOL