I once was headed for a week in Death Valley and, as a paranoid drug neophyte, I was on the fence about bringing my little two-dose baggy of magic mushrooms. I was thinking of ways to conceal them when I panicked and decided to leave them behind. Except I didn't — somehow in my frantic packing, the little baggy found its way into my checked bag.
When I opened the bag in Vegas, on top of everything was a TSA notice like the one in the photo above. The corner of it had been painstakingly stuck into the seal on the baggy of mushrooms.
I took it as the TSA person sending me a message: "I see what you did here; now go have fun in the desert." So that's exactly what I did.