Long story short: he met his future boss at a carwash while they were talking, boss wrote down his number with a description of where he met him rather than a name, introduced him as the guy from the carwash to all the new co-workers, and everyone just started calling him Carwash and the name stuck. Not a lot of people even know his real name anymore. I’ve heard it before, but I don’t remember what it is.
My Buddy, Carwash, In His Tree / Leica M (Typ 240) (beehaw.org)