I don’t think any other auto-correct fails can out beat this one.
A few middle school and high schools in Gainesville, Ga. were locked down because of a student’s text message, which says, “gunman be at west hall today”.

The message was accidentally sent to a community member’s phone, and the member called the police. 
The student intended to say, “gunna”, but auto-corrected to “gunman”

The police then tracked down the sender, and realized it was an auto correct mistake.
Sgt. Stephen Wilbanks of the Hall County Sheriff’s Office told The Times, “We want to emphasize that the recipient did the right thing in reporting the message.”

So much for auto-correct!