Crustache Share definition Flag A term invented by Bobby Veto to describe the dried remnants left in a mustache after you've performed oral sex on a woman. A crusty mustache. I had to put Saran wrap on my upper-lip before I took a shower so it wouldn't ruin my crustache. Crustache by Porgy McDuffin July 25, 2007 Get the Crustache mug.