I dressed up as a huge envelope with the command's address and some bogus looking return address and stamps. I had a bottle of talcum powder inside and could squeeze it to get talc to come out of the seams. Sort of flopped, especially with the mail handlers.
I played it off as a way to increase awareness. That was a success!
At least I didn't where my long white shirt, turban and my AK ... but at least I wouldn't have got a huge paper cut [:)]