Someone that is obviously on crystal meth or some other type of speed, that looks around at all of your belongs.
When you leave the room the lurper(s) can't help looking through your shit. Even if they go in your baby's room, a true lurper(s) can't help but go through even the kids' shit.
Someone who thinks they are nifty with computers but spends all their time commenting on youtube videos and bugging 'celebrities' for retweets and mentions. Basically just browsing the surface web.
"Hey, did you see that new kid? He's pretty clever."
"Nah, he's just a surface lurker!"
A foul smelling yellow eyed creature from the back alleys of Detroit that comes out at night to gather your belongings while you sleep in order to fulfill his crack motivating mission.
Damn that swamplurker bastard from the alley two streets down stole all my shit out of the garage last night.