Reminds me of a page I found way back, where a guy tested to see just what kind of things he could get delivered through the postal service. I tried digging it up but can't find it.

He mailed a lot of things to himself, but there were two that stood out.

One was a brick, IIRC not wrapped, just taped address and stamps to it. It arrived with some delay, in a bag, smashed to pieces, likely in search of drugs.

The second was a full-sized cod or similar fish. Can't recall if he wrapped it. In either case, the fish did not arrive.

Instead he got a stern warning that if anything like that ever happened again, he wouldn't get any more mail delivered, ever...

IIRC apart from those two, most of the weird attempts were delivered successfully.