A person who, when some people are playing a split screen video game in which the object is to kill everyone else, and somebody looks at another's screen to see where he is and then ambushes him/her.
R Plant: The only reason you killed me was because you looked at my screen.
Bon Scott: No way!
R Plant: Screen hopper.
A person who watches the screens of other players while playing a first-person shooter (FPS).
That guy only wins because he's a screen hopper