Top Definition
An STI that slowly overtakes all brain function and at the same tame amplifies many specific brain waves. These brain waves increase hand eye coordination, motor function, reaction time, and overall lethality. Through lab testing this dreaded infection has proven to leave the afflicted with an overwhelming desire to hide in shadows while wearing all black. The disease was named "ninjitis" because in extreme cases the afflicted have been left with an additional need of seeking training and becoming a full ninja.
I think Kyle has ninjitis. I never see him anymore and he's always wearing black.
by blizzard55555 July 28, 2009
1 more definition
A viral infection transmitted by Ninjas and Ninjinas. Unknown in origin, this mysterious disease will be around just as long as those damn lazy ninjas
that ninja snuffed my duff now i have to get two shots in my throat every day to keep my ninjitis at bay
by bob hastills October 10, 2005

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