When you whisper something in his ear while rubbing his arm. It drives him absolutely crazy.
When your hand "accidentally" touches certain areas. It makes him blush and all you do is smirk at him.
When you bite your lip. He thinks about kissing them and the other things those lips could do.
When you kiss his neck. All it takes is a few pecks and he starts blushing heavily. It sends shivers throughout his entire body.
Anything you do turns him on