It reminds me of the "true" story I posted in a different thread quite a while ago:
Here is a Daimler Benz story that was told in the 70s:
In the late 50s, a well-to-do or prominent person bought a Mercedes 300 W186, nicknamed "Adenauer" after the first chancellor of the federal republic of Germany after WWII.
The customer took delivery and after a few days returned to the dealership with the complaint of a mysterious rattle and cluck in the car.
Service checked the car out and did not find anything.
The customer left but came back after a few days with the same complaint.
This scenario repeated itself several times until Daimler Benz decided to buy the car back and provide the customer with a replacement.
The rattle and clunk car was shipped to Untertürkheim to factory service, where they started to thoroughly inspect and subsequently disassembling the vehicle.
When it was down to the bare frame and nothing was found, they cut the frame apart and - behold - inside one of the frame tubes they found an empty beer bottle that one of the assembly workers slipped in there before it was welded...
Not sure if any other of our German members ever heard this and can add something to it??