A bathroom act performed by a female, in which she wipes her feces from back to front. It leaves a particularily foul odour -- or flavour if you were in a rush -- that grinds oral sex to a halt.
"I must have pissed her off, because she gave me the brown carpet treatment last night."
"That chick I went home with last night was kinda gross. I could ignore the other stuff, but the brown carpet was the final straw."