Top definition
A booger (dried nasal mucus) that gets hard and sharp enough to stab or cut the inside of your nostril. It can result in pain and sometimes a nosebleed.
"Dude your nose is bleeding, what's wrong with you?"

"The low humidity today gave me a really bad knife booger and it cut me when I was trying to pick it out."
by SR20DEN December 24, 2009
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