A noun usually used to replace the insult "pussy" or to describe a girl who is very permiscuous and is known to have a loose vagina. Reference of winsock deals with the floppyness of the vagina as it would appear blowing in the wind.
When one man is penetrating another man up the bum, goes in too deep, thus resulting in second man's intestines being pulled out his rectum, resulting in something that looks rather like a windsock.