A term used to describe the effect on a man's penis when having doggy style intercourse with a woman who wipes from back to front, thus leaving a small amount of feces around the entrance to her vagina.
My friend was fucking Misty from behind, and after he pulled out he noticed he had brown rainbow. Misty is a dirty ho.
by JasonW October 27, 2005
taking a dump two feet behind someone's bedroom door then closing it behind you.When the chump opens the door all the way he smears the turd into the carpet in a lovely rainbow design.
they'll be scrubbing that rug for a week before they erase the brown rainbow I left them
by rod fury April 20, 2006