The stage of a young mans moustache near the end of his adolescent years. When the hair above his upper lip looks more than just smeared dirt. The hair grows long and prickly. If you were blind folded and someone told you to run your finger across it and you had to guess what it was, it would be a caterpillar.
The BIG caterpillars with long spikey hairs you see on leaves, but instead above a young mans upper lip. There for called a lip caterpillar.

Conversation ex:
Gal- "What's that on your face?"
Guy- "Oh this? It's my lip caterpillar."
Gal- "May I pet it?"
Guy- "It might bite."
by Cosmosmosis January 18, 2012
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