Mine dates back to a big fire at a school where I used to work - I was a lab technician and the labs were out of use. As I could use the school switchboard and type, I helped out in the office (which also meant the office staff had time to sort out the smoke-damaged strong-room contents). The office manager emerged from the strong-room after a session clearing out looking particularly grubby ... one of the other office staff was called Sue, so they instantly became Sooty and Soo, the third permanent member of the office team being Sweep! Me - I was the one that turns up every now and again, causes trouble, then disappears - Little Cousin Scampi! It stuck and has been with me ever since .... nearly 20 years now!!