thanks all for your advice!
after thinking about this for a while i've come to this conclusion: next time he does it, i'll report him. i'll talk to my group manager and tell what happened. before this i will tell someone else on the same flight in order to have some kind of back up. if, for some weird reason, i would get a reputation of a troublemaker etc., i will just live with it. i'm flying with the guy next roster so we'll see what happens. of course i will tell him as well to keep his hands off me. again.
happy landings everyone!