I've also got a fun one like that from working security!

I was working the solo overnight shift during Christmas break at a factory & noticed a gift-wrapped cylinder sitting in one of the common areas. I picked it up to bring to the lost and found & decided to see if there was a name tag or something. Well, there wasn't a nametag, but there were a few wires poking out that made me realize I was possibly holding a pipe-bomb.

I called 911 while freaking the fuck out and was told to stay calm and very still while they sent someone to save my sorry ass. After about 30 minutes the Michelin Man's blue cousin strides in, asks me a few questions, & decides it would be safe enough to take the Christmas gift from hell outside to deal with.

While the bomb was being taken care of I took a few cops to the security room to download all of the footage from the past few days. Turns out the gift-wrapped grenade was juuuust out of the cameras view & there was no way to tell exactly when it had been left there.