1.) Having sex with one person, leaving them and having sex with someone else unbeknownst to the first and, finally, returning to the first and banging them a final time, all within a short period of time.
2.) A person who particpates in such a sexual excursion.
1.) One night, in the Geen, the girl had a bookender.
2.) After the fun the night before, she was officially a bookender.