You hear stories of people getting their finger nail clippers taken away, sewing kits, etc.. Well on my trip to Puerto Vallarta I took a knife with me. Not a tiny little discreet knife, but a nice big multi-blade knife.
I did not do it intentionally. I simply had it in my camera bag and hadn't used my film camera in some time, but did not have enough memory for my digital to store pictures for a whole week, so I took the old film camera. It was not until being in Mexico for a couple of days that I went looking through my camera bag for something and came across my knife. I guess it lets you know that things get through. I also had a couple of screwdrivers right next to it. Needless to say those items made the trip back in my suitcase and not my camera bag which I had carried all the way down and intended to carry all the way back.