A beautiful term for an extremely Foul smelling fart. The term is made funnier if the fart sounds like quacking duck when expelled from the rectum. Though an SBD can still qualify as a Butt Duck if it is especially foul (emphasis on the word foul/fowl for comic effect). See frequently activated rectal tremble and shit flavored air.
"Fuck Mary, you shit a butt duck! I think you have cancer, something has crawled up your arse and died!"
by Keifermail August 08, 2009
the sound produced by air rushing past an anus resembling the sound of a duck.
everytime I eat beans, I swear there is a buttduck in my jeans.
by your mom September 03, 2003
A baby duckling that is lodged up the anus after sitting on it at a very young age.
My butt duck burps farts.
by Scotgirl1027 December 19, 2010
stinky farts that sound like ducks coming out your ass
alyssa has a butt duck.
by Corinne_creep December 08, 2008