Typo Ninja 

The person who is responsible for spontaneous occurrences of typos or other errors within text.

Guy: ring over the textbook when you come
Girl: ... what?!
Guy: agh, I meant "bring"! The Typo Ninja struck again!!!

Person: I waers going to the store
Person 2: Whoa, Typo Ninja got you there.

Typo Ninja by Kelila December 1, 2009

Ninja Typo 

A Ninja Typo is a punctuation or grammatical error that does not reveal itself to the author (no matter how hard the author looks for it) until it is too late (i.e. after it has been published in a way that cannot be retracted).

Example : Dang! I proofread this email 3 times and I STILL managed to leave the "l" out of "turtle". That Ninja Typo just killed my chances of getting re-elected.

Ninja Typo by Mank002 October 22, 2014