I had to laugh at a story that I was told a few years back (probably not actually real, but made me chuckle)
Back when microchips were first really being used commercially en masse, a British company ordered X thousand chips from a Japanese company, with Y% tolerance of failure.
The Japanese apparently sent 2 consignments- one with 100% working chips and the other with a box of broken chips, as per the requirements of the requirement. Along with it they sent a note "Why do you want broken chips?".
The point the Japanese were making was that whilst we expected a % failure, they did not and only accepted 100%. How true it is, I don't know. But I could just imagine it happening.
Stu