Sort of like a rebound gf or bf, but used only with friends. If one friend is pissed at you then you go see another (even though you might not want to) because you aren't gay enough to be seen without someone else, then he/she is your rebound friend
PissedGirl: I'm pissed at you, eff off!
Friend: *walks around for a while then decides to see another friend because she looks like a retard walking around alone*
ReboundFriend: Hi, what are you doing here
Friend: She's pissed at me so I came to see you
ReboundFriend: What, so I'm your rebound friend?