If girl/boy is dumped by their boyfriend/girlfriend and is crushed, and then another boy/girl sweeps her/him off her/his feet, she/he becomes the rebound.
*Based off of Basketball: Someone(1) couldn't score, so someone else(2) picked up the rebound(3) to give it a try.
(1): The person doing the dumping.
(2): The person picking up the dumpee.
(3): The person who just got dumped.
Boy 1: "Hey, you're with her now?"
Boy 2: "Yeah, she just got dumped by her boyfriend. So I picked up the rebound."