I had a similar experience, called for jury duty... I report in, and empty my pockets. I had left virtually everything in the car that I thought could get me in trouble, including my "other" key ring with the fire starter, Leatherman, whistle, etc etc... what I forgot was that on the key ring that I actually use for keys, I still had a tiny SAK (1 inch blade). I mostly use that for the tweezers actually.

Anyway, I didn't even notice it when I dropped it into the little bucket with my change, watch, cell phone, wallet... so then I walk through the metal detector, and the little bucket is going through the xray and I hear (in a very loud voice) "YOU DIDN'T REALLY THINK WE'D LET YOU BRING A WEAPON INTO THE JURY ROOM DID YOU?"

When my fellow jurors saw the "weapon", they all started laughing, which didn't really go over very well with the security folks. I guess if I was Crocodile Dundee I would have pulled out a machette and said "that's not a knife, THIS is a knife" <img src="/images/graemlins/grin.gif" alt="" />