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1.
Something you'll never survive.
Ninja: "SHORYUKEN!"

Bystander: AAH! Ninja attack!

And then everyone dies.
by TZScribblez December 03, 2007
 
2.
When prisoners wrap shirts around there heads to make a mask and go attack fellow immates,The very same tradition my own Father started.
Tray - Yo dogg let's Ninja this foo.

cop - All we saw was eyes.
by GDOGG October 31, 2004
 
3.
its when your embarressed about being on wellfare,and your about to pull out your bridge card. Instead of calling it that you say ninja attack!
Hey your total is 5.50
hang on let me pull out my ninja attack!
by courtney and jeremy!!!!!!!! October 11, 2007
 
4.
1. when someone comes completely out of nowhere during a race or any other event.

2. fighting a single person or a group of people like ninja
"That guy was in last place for the race but he just Ninja Attacked us."
by y.cole March 03, 2012