Australian slang. A matress which someone has munted (vomited) on. Muntress can also include sweat, piss and pool water.
by M-ASS O-Camp07 December 14, 2008

Comes from the term Falcon Punch and munt. When someone is about to munt (vomit) they scream Falcon Munt! as loud as they can, and attempt to munt in the most impressive way they can (ie, uberprojectile).
by M-ASS O-Camp07 December 14, 2008
