The particles of shit crumbs and ass matter that stick to the freshly laid strip o'jizz on a whore's upper lip after someone farts in her face.
I hadn't wiped in two days. That was a REAL dusty mustache.
by AmyKristinaChuck February 04, 2008
what you receive when providing cunnilingus to an old dried up pussy
Ms. Butterfield down the street gave me a dusty mustache
by hahahahahahailovewhitters November 12, 2014