...from Rolling Stone
The music to “The Jean Genie” was inspired by Bo Diddley’s “I’m a Man”; Bowie wrote the song’s lyrics in the New York City apartment of model-actress Cyrinda Foxe, then a publicist for his management company and later married to David Johansen of the New York Dolls and Steven Tyler of Aerosmith. But the actual subject of the song was Iggy Pop, or at least a fictionalized version of him, Bowie said. The lyrics were about somebody who “sits like a man but he smiles like a reptile.” The title of the song was an homage to French novelist/dramatist Jean Genet – Bowie has told different stories over the years whether the reference was unconscious or deliberate – while the line “He’s so simple-minded, he can’t drive his module” would, in turn, inspire the name of the band Simple Minds.
as you say, probably written while out of his box on some recreational chemical or other