How about KNOWING you left something on the plane, and STILL not getting it back?

Coming back from LAS into LAX, as I got up and I heard my cell phone drop out of my pocket and clunk on the floor. I stop immediately, step out of the aisle, and get on my hands and knees to find it. I scanned at least 10 rows within my seat, and when everyone left, I searched the whole Y cabin (on an MD80). The FAs were great, and a couple of them even got on their hands and knees to help me find it. I even searched under cushions and under powerplug boxes in case of the bounce factor. NOTHING.

Told the GA, we went back and looked again, and NOTHING.

Called lost and found, left a message, and that's it. The only plausible explanation was that another pax scooped it up immediately and walked off with it.