Another term for cock ring. A ring of either rubber or leather that is placed around the scrotum and penis to constrict the flow of blood to the male organ, allowing for larger, longer-lasting erections and more intense orgasms. Also worn to make the male pubic region stand out better, making the bulge in one's pants more pronounced so that other men think you have a bigger package.
I used a rubber o-ring that was too tight and my boner wouldn't go down. Now I can't get the fucking thing off.