Someone who is extremely proficient at stealing cookies without being spotted, regardless of how many people are in the vicinity.
Guy sees cookie.
Guy reaches for cookie.
Cookie disappears.
Guy cries.
Cookie Ninja has won.
by DLTZ April 28, 2013
Get the Cookie Ninja mug.
When you throw a fart into a persons face.
She released the gas and ninja cookied her sister, causing her to gag.
by kaylacatcher97 November 18, 2016
Get the ninja cookie mug.