A person who demonstrates severe and regular mood swings on their facebook status updates. A condition usually found in females.
Males will often continue to be their "friends", probably in the off chance they get the opportunity to get into their Bra one day.
"Dude, whos that? Her dad died this morning, but now, she is all good agan after getting her new fake Burbery handbag off of Ebay!? Is she on drugs?"
"No mate, she just has Facebook Bipolar. I'd still shag her though, Hence we're still friends....just incase. You know?"
"Ah, yeah, OK. Gotcha. I know a Bipolar facebooker too. Annoying aren't they?!"
"Tell me about it dude.... tell me about it!