I read somewhere that a railroad track width is based on the width of 2 horses' rears. This in turn influenced the size of the space shuttle.
Somewhere else, a company's supervisor would write "0" on the front page of every report, because that was the way it had always been done. Nobody had any idea what it meant. On investigation, it meant there were 0 air raids that day, a practice started during a war.
Another one, an experiment: a bunch of monkeys in a room. The room had a comb of bananas hanging over a ladder. Every time a monkey climbed the ladder to get the bananas, the experimenters would spray all the monkeys with cold water. Eventually, all the monkeys learnt not to try to get the bananas. Replace 1 monkey. The old monkeys would prevent the new monkey from getting the bananas. Continue replacing monkeys until all the monkeys are new. They would stop any monkey from climbing the ladder, but none of them knew why. Here it is in comic form:
This post is to collect things like these.