Bob: Tim, how'd that hooker work for you, did you finally lose your virginity?!?!
Tim: No, turns out the money I payed went to a Foreplay Whore...
Bob: Awwwww... lolumad?
When one thing leads to another and you end up in bed with someone already in a relationship. They both "use" each other for their own personal gain, but in a way still care for each other.
My girl friend goes to a college far away and I missed her, now I went ahead and made things worse by making a "foreplay oops" with a girl.