This reminds me of a guy in 2007 whose curiosity got him to cram around 34kg (75lbs) worth of lead bricks into the Japanese postal service's ExPack 500 flat-rate envelope, which had a supposedly 'impossible' limit of 30kg (66lbs) and were usually not checked for weight when sending. The post office clerk wrestled with it and eventually agreed to ship the thing. He didn't actually send it though.

https://sites.google.com/site/fluordoublet/%E3%83%98%E3%83%B...

A few years later, the ExPack was deprecated and replaced with the LetterPack envelope, which now has a limit of...only 4kg (8.8lbs). Hah!