Nap wood derives from the word morning wood. It means when you take a nap and you wake up, you have a woody. It's common during class.
Dude 1: I got nap wood man
Dude 2: I hope the bell doesn't ring or you're going to be late for your next class.
by Aaron M. April 26, 2005
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When a guy awakes from a cat nap with a boner
Dude 1: Hey man, you got some major Cat Nap Wood!

Dude 2: Yeah bro i just woke up and i had a dream about your mom.
by onleemortall December 12, 2011
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