1.) When multiple partners, usually 3 or more, engage in blogging or chatting on Facebook.
2.) Chatting it up with a bunch of bitches on Facebook.
Guy1: "What you been up to?"
Guy2: "I've just been facebanging bitches all day."
The act of exchanging sexual messages via facebook chat. Basically, sexting on facebook.
Ratt and I were Facebanging until 8:00 this morning. I was so wet.