Sharing is caring and frankly it ain't no fun if my homie can't have none... You know what I'm saying. Anyways on a serious note it's always cool to have an extra slut to spread you sperm on or even a buddy with you to help dick down that really horny cock craving bitch.
Who says you have to stop at three? A small orgy of people enjoying group sex can be really fun but things can get really sticky.