Great stories, good to know I'm not the only one who has experienced them.

I had to watch while consultants destroyed a project. It read two files for orders, the order itself and the client who ordered it with a simple key relationship. Simple enough. They decided to complicate things by shuffling the data into several files they designed and add their own keys. They read the client, and called a function that got the key from their key table and incremented it. then read the order and to get the foriegn key that pointed to the client, called a different function that got a different key from their key table and incremented it.

Somehow it worked for a couple months. They never provided design documents with any detail, so I was not aware of this until during parrallel testing it created orders that had the wrong return address on every order. (We sent orders as if they came from the client).