facebook popper
A Facebook popper is a person who logs on just to see who's online and then logs off like they're being chased by a swarm of bees.
I logged on, saw my crush was online, and popped off like I just got stung by a thousand bees.
He checked who was online, saw no cool people, and logged off like he was running from a dragon.
She logged on, saw no one she liked, and popped off like she just lost her favorite shirt.