The crusty brown material that gets transferred to the rear of the toilet seat or underwear, resulting from the accumulation of fecal matter at the top of an unclean, too-far-rear-wiping person's ass crack.
I almost sat in the hefty butt smudge that you left on the seat!
by Etch August 15, 2006
2 more definitions
after 'releasing' waste products, the part that 'hangs on'. also an insult to persons of idiotic disposition.
'you dropped that expensive glass! - you butt smudge!' or 'ewww...my undies are stuck to my butt...it must be that little be of butt smudge left'
by mel p November 30, 2004
physical proof against a wall that a couple committed adultery in a baby nursery
Craig totally cheated on Holly J with Manny! I mean danng, check out the butt smudges on the wall.
by omgitskee June 01, 2011