A guy who thinks he's gotten lucky since an attractive girl with a low self esteem decides to be with him. In reality, the girl is only dating him because she's trying get over another guy (A.K.A. she's "on the rebound
"). The opposite/converse of this would be a rebound chick
Cynical Friend 1: What the hell does she see in him? She's way out of his league.
Cynical Friend 2: Oh, it's nothing serious. She's just trying to get over her last breakup. To her, he's just a disposable rebound guy.