My UK Survivor set off a detector once, so I just don't wear it. But that's not the Fun Fact:

I wear two silver bracelets on my left wrist, clipped together and not easily removed.
Going to the DMV on a very slow day years ago, the experienced guard was on duty solo,
and after my first trip though with a beep, he took one look at my wrist and said,
"Hold it up by your head."

That done, no beep!

Since then, I have scratched my head with my left hand through every detector, and naught a blip, beep, or even query from the TSA.

When I can, I pass the tip along to ladies whose rings set off the alarm, and obviously do not want to let that rock out of their sight.

Theory: Metal weapons of any effectiveness can't be concealed above the neck. Mental ones can't be detected.