Uncomfortable. I had a guy message me, telling me that he was masturbating to my profile picture on twitter and I asked him to stop and he wouldn't
It would find it creepy!
Well as long as they're female I'd like to meet them and perhaps do it for real.
That would depend on who was doing the masturbating.
Flattered if they look good, creeped out if it's someone I don't like.
I would have to feel that they were a seriously disturbed individual.
Depends on how old I am in the picture