I found a healthCheck function while troubleshooting an old application for a large auto manufacturer today. The healthCheck function was running several times a day on a timer. The function tries to insert a record into the database and returns whether or not it was successful. It was written in 1999 and has to date inserted over 2.5 million records into the database! 1/3rd of the data for this application was the same record.

How the hell did nobody notice this for 20 years!!!