Be as (something) as all get-out phrase
Said to stress a description of a quality or feeling, especially an unpleasant one.
I thought that movie was as boring as all get-out, but the kids loved it.
Oh man, I couldn't sleep a wink last night.—I'm as tired as all get-out now.
This kind of experiment seems to be as cruel as all get-out.
The phrase originates in the late nineteenth century without the word all (e.g., as getout). One of the first instances of its current form in print is the American novel Huckleberry Finn.
To do domething based on your emotions rather than for rational reasons
I can't believe that Tom beat his classmate. He's always the one who let his heart rule his head.