This one couldn't run a hamster wheel.

It's my favorite way of expressing idiocy in people. Just slightly more favored than "they're not the sharpest stick in the sharp stick drawer."

Earlier today this happened:

Me: The last digit in your password is a zero, not an O.
Customer: you mean it's a number, not a letter?

Just a couple minutes ago:

Me: He's not in until 4 Chicago time.
customer: so, it's 1:30 California time and we're 2 hours behind, so he's in now?

How do these people function in the world?

Inquiring minds want to know.