Top definition
An exclamation you make when you realize something you should have known all along, or when the person you're with has a startling revelation about something obvious.
Bob: "Wow! I never knew that donuts were so bad for you!"
Sally: "Duh 101"

Francine: "I should have known he was married! Duh 101!"
by zandwich October 05, 2010
Get the mug
Get a Duh 101 mug for your barber Bob.