Shag Knees
When the knees are sore, swollen, in pain or have friction burn from having vigorous sex on a carpeted floor or rug. The heavier the carpet shag the worse the condition.
Wow girl. What’s with your knees? Looks like you fell off a bicycle. Naaahhh. I got fucked six ways to Sunday’s last night on the living room rug. Just a bad case of shag knees.