A colleague from 15+ years ago had an unfortunate habit of using filenames like "poo" or "shit" for writing debug output. One morning, the inevitable happened:

A colleague from 15+ years ago had an unfortunate habit of using filenames like "poo" or "shit" for writing debug output. One morning, the inevitable happened: a very angry client phoned up complaining that his site was swearing at him. It turned out that the debug log had filled up, causing the site to crash on load, displaying only a single line: CANNOT OPEN SHIT The lessons you learn early on in your career.