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An inexplicable, noticeable, callous on any little toe on one's foot which can only seem to be explained by one doing ninja like acts.
You sit and rest one foot on the table. Roommate notices an ugly yellow scab looking thing on the middle toe of your foot.

(Roommate): "Dude! How did you get that callous!?"
(You): "Wtf!? I don't know! It seems like some kind of ninja callous!"

Knowing that you weren't up to any ninja-like activities, you decide to pick at it, then realize its a piece of dead leaf.
by Koo guy March 26, 2012
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