I would like to take this opportunity to comment on a common tactic employed by many, such as TV's Columbo, but more often used by a certain sort of unregenerate Son of the South. I'm talking about the tactic of deliberately appearing to be stupider than one is. This is often a reflexive habit, honed into such persistent usage it becomes almost unconscous in its employ. I assume the prime role model in this behavior is Andy Griffith. In this fictional display, Andy appears to be a hick, and beguiles the bad guys into letting slip some critical piece of intelligence, thinking he won't pick up on it. But he does! This is because Andy is sly.
I believe the practitioners of this habit, even though they believe they are emulating a smart fellow, have practiced this routine so much that they are in danger of actually becoming the thing they think they are pretending to be. Like your Mama said, if you keep making that face it'll get stuck that way.
Besides, I asked myself a while back, how smart do you have to be, and how smart is it, to constantly make people think you are an idiot, anyway?