One of my first jobs after high school was in retail sales at Sears. My boss, Richard Tracey, aka D i c k (censor!!!)Tracy, had a loud booming voice that carried throughout the store. Mr. Tracey lived in the country and had a rather long commute to work but when some of the people from the country used to show up at the store, Mr. Tracey would loudly greet them by exclaiming, "Mcginkleschmidt!"
I suspect that Mr. Tracey had facial recognition of the people but couldn't remember their names so by greeting them with the odd name of "mcginkleschmidt" he was probably acknowledging them as someone he knew from the country.
Over a period of about three years that I worked at the store, Mr. Tracey must have greeted hundreds of people with the loud announcement of "mcginkleschmidt!". When the Internet came around and I needed a screen name, "mcginkleschmidt" came to mind and I've used the handle for years.