jorsher ~ a sicko who does this in public.
I once had a jorsher on the beach. Once I got over my disbelief I stood up, grabbed a water bottle (the closest thing I could find, evidently I felt stronger with some kind of weapon, why should he be the only one with something in his hand?), and shouted at him to piss off.
The most insulting part, I don't even think he'd been looking at me, but at two topless chicks sunbathing a way off. Slappers.