What does “Don’t leave your brains at the door,” mean? Is this an idiom, or just frequently used phrase?

I found the phrase, “Don’t leave your brains at the door,” in the statement of Republican congressman, Morgan Griffith quoted in ‘Today’s Quote’ of Time magazine (November 18). Under the caption, “I hope you didn't leave your brains at the door,” it reads:

“A Republican congressman from Virginia, to Secretary of Energy Steven Chu. Chu has been assailed in congressional hearings for claiming to have had no real-time knowledge of key events in the collapse of solar energy company Solyndra.”

“Don’t leave your brains at the door,” reminded me of the famous catch phrase of Amex Card’s, “Don’t leave home without it” that prevailed in 1980s. But I don’t understand exact meaning of “Don’t leave your brains at the door.” Does it mean “Don’t be silly (or oblivious)”?

I could find a few examples of the use of this phrase on Google, e.g.

-"Have I ever walked out on a movie? Not yet. This is the closest I've come. Just the first in a line of soon to come Robin Williams crap. Maybe not technically a "*leave your brain at the door" film" -.Amazon.com

-If you live in a confessional world, do you need to leave your brain at the door? There’s been a lot of talk lately about whether Roman Catholics have less intellectual freedom than other Christians because of the strongly confessional nature of the Catholic tradition.- Scientia et Sapientia.

As far as I checked, none of Oxford, Cambridge, Merrimu-Webster registers “leave (check) one’s brains at the door” as an idiom. Nor Google Ngram viewer registers usage of this phrase.

Is this phrase has a currency as an idiomatic phrase nowadays?

Solution 1:

My guess is that it borrows the idea of leave your coat at the door. When you enter a theater, you don't need your coat any more inside the theater until you are to leave it. Similarly, leave your brains at the door means you don't need to use your brains from now on until you quit. Just my personal understanding.

Solution 2:

It's an idiom. Leaving one's brain at the door means you are not engaging the intellect, whether that means a mindless movie plot (if you think about it you realize how dumb it is) or not critically evaluating what you hear in a speech. So "don't leave your brain at the door" is meant to caution you to not take things at face value but rather to think about them.

When this idiom is used in an area where there is disagreement (e.g. politics, science research, religion), the person imploring you to not check your brain believes that "the other side" talks a good game but doesn't stand up to scrutiny.

Solution 3:

To leave something at the door is to abandon it. It's a common metaphorical formula, but no specific instance is an especially common idiom.