The sexual act of sex with the breasts in which the female lays down on her back while the male, facing her feet, proceeds to fuck her tits, rubbing his bum hole in the female's face. For extra pleasure, the woman's nose can be used to stimulate the man's anus.
If you perform the brown unicorn, you are a dick.
by Neil Tuuri October 25, 2006
When one straps a dildo to ones forehead and bangs another in the ass. Neighing and frolicking in the process.
Sven worked the brown unicorn on my turd cutter like Legend last night.
by abz to the rock July 01, 2011