Something you pull, mentally, when you realize that something that is happening to you, to a friend or some random person is totally crazy
Dude 1: Hey man. You hear about that guy who wanted to date a 18 year old?
Dude 2: No. What about him?
Dude 1: Man is 80 fucking years old.
Dude 2: Damn. Time to pull the WTF alarm on that.