When the man on top during double vaginal
sex pulls out and cums on the other man's scrotum. After using his
dick to rub the cum all over the scrotum, he then re-enters the girl's pussy to cum again on the other
guy's shaft. Due to the homoerotic nature of the act, it is mostly performed by bisexual men. However, straight men can perform it on occasion.
My bi friend and I once did double vaginal with a girl we picked up from the
club. I was on top, so I decided to give him a
slimy joystick since it was his
birthday. I don't like guys, so I told him that's as far as he would get with me.