A person whether it be male, female, or whatever who will only engage in sexual intercourse or activity when it takes place during an Orgy, usually involving a minimum of 5 distinct persons (animals not included).
Robert: Man, I spent three hours talking up Helen last night and buying her drinks thinking I was going to score, but wouldn't you know it she's an OSexual and wouldn't go back to my place unless there were two more couples going to join us.
Shawn: Shit! I wished you would have called me as I was out with the Mrs. and our neighbors Heather and Bill. They were both loaded up on Pino and cocaine and would have been down for anything...especially cleaning Helen's butthole.
An old person that watched football in the 70s that constantly Overrates OJ Simpson and completely ignore that he was a double murderer because he was a good football player.