A mustache grown specifically for the purpose of fraternity rush. Usually only done by older fraternity men during rush as a sign of experience rushing potential new members.
Irritated skin on your upper lip, making it look like a mustache, which is especially unfortunate for females
After using Nair on her upper lip to remove her girl mustache DESPITE the instructions not to use it on the face, Kaitlin was rewarded with a handsomely dark rashtache