Any person that when they bend over has hair coming out of their butt. Referred to as a "rainbow ass" because it is popping out as rainbows do from clouds.
by kgriff January 06, 2012
by Momo Hatake May 07, 2007
An imaginary meteorological event occurring after a severe bout of diarrhea, much as a rainbow occurs after a thunderstorm.
by Barbiste May 26, 2004