by Reagan Lausche February 21, 2005

A scary ghost creature in the Mushroom Kingdom. Mario faces these a lot. These pearly-white ghosts will become invisible if anyone faces them. They usually cannot be disposed of. There are also other Boos, like the Big Boo, King Boo, and more.
by SeaCaptainDrake December 6, 2003

by Patricia Reyes December 14, 2008

by medium bro December 6, 2006

by giantdick-O-tron June 20, 2011

Boos is never given a concrete definition, only prefaced when its used with any context at any time, and may be used for both negative and positive reasons in the same sentence.
Person 1: i got the hookah.
Person 2: is it boos?
Person 1: its pretty boos.
---
Person 1: when you rollin in?
Person 2: tues night
Person 1: boos
---
Person 1: I'll be over in like 10 minutes.
Person 2: Boos.
--
Person 1: so hows phil
Person 2: Boos
Person 2: is it boos?
Person 1: its pretty boos.
---
Person 1: when you rollin in?
Person 2: tues night
Person 1: boos
---
Person 1: I'll be over in like 10 minutes.
Person 2: Boos.
--
Person 1: so hows phil
Person 2: Boos
by Geem-Unit July 16, 2008
