by justout October 02, 2006

Also known as the penis. There is no muscle in the penis, the penis is erect by a massive rush of blood. Therefore another nickname for the penis is the Main Vain.
by Butcher Jadali August 27, 2009

by Nttm May 19, 2010

by gareth matthews February 01, 2007

did you hear about Leslie!? last weekend she was railing the main vain on a cruise ship and now shes married to a 65 year old millionaire.
by Jerry Himself August 02, 2017
