It can be even more irritating then someone who reads the newspaper over your shoulder. often makign you so uncomfortable to the point where you are unable get any work done.
This class of person will often read over your shoulder trying to not be to obvious and then 30 seconds after you close your browser window or make eye contact with them will immediately look away and deny they are reading over your shoulder or have the nerve to comment on what you were doing.
"umm sir, i can not work with you screen perv all over me."
Max is running around cant find Tim, so looks at Tims halve of the screen to find his position then throws a grenade which explodes
Tim "Oh man you're such a screen perv"
Max "hey it was just luck, I am not cheating honest"