Jerk-lurker

Or jerklerker, is a person who intentionally Jacks-off around one person or in public.

"I was pissing in a bush till i saw the eyes of a jerk-lurker staring at me, then I heard the beating of meat"

"I was in a McDonald's bathroom stall when I saw the dude next stall over was jerk-lurking around all these poor souls, so I started banging on the stalls wall and scared him away."