Top definition
The unexpected,unprovoked erection that occurs while in public. Usually characterized as coming out of no where, particularly in the morning (at work or in class)

Scholars maintain that it a
reverberation of morning wood...
similar to an after-shock associated
with earthquakes

Morning wood is to ninja wood as
Earthquake is to after-shock.
This morning, in my math class, I had a mean case of ninja wood that came out of nowhere. (It snuck up on me like a stealthy ninja)
by Chris A. P. February 07, 2007
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