The Origin of SonOfSofaman

Where did the nickname "SonOfSofaman¹" come from?

The story goes something like this:

Robert was making fun of the fantasy novels he thinks I read (which I don't). Specifically he was poking fun at the way fantasy authors make up names for places and people. Robert is of the opinion that authors who stitch together weak plots revolving around characters with names like Londor Riverbender and K'thar Gruenthor are not writing legitimate literature.

Somehow (this is the part I'm sketchy on), the conversation turned to the Superman stories. When someone mentioned Jorell, Father of Superman, Robert's habit of unbridled free-association conjured up "Jo-El, Son of Sofaman", and the name stuck.

¹ My father does not sell, make, or re-upholster sofas or furniture of any kind.