Celebratory and reminiscent of a hi five
but sexual in nature; a sexual handshake
properly performed on a female (usually) with vaginal entry of a penis encased in a condom and the giving partner rotating their penis through as much of 360 degrees as possible while inside the female's vagina. The 360 rubber-five is the crowning moment of their sexual relations and actually the sexual hi-five or handshake which celebrates the good sex just had by both.
A mind blowing sex session which culminates with a 360 rubber-five sexual "handshake".