A reference to a favourite film - 'Dark Star', a science fiction black comedy (a genre of one?), the film school graduation project of John Carpenter (who went on to fame with the likes of 'Halloween', 'The Thing', and 'Escape From New York') and Dan O'Bannon (who later reworked some of the ideas in his script for 'Alien'). The Time Out Film Guide once called it "the last great hippie movie", and Carpenter himself characterized it as "a sort of 'Waiting For Godot' in Outer Space".
The leading character, played by O'Bannon himself, is ostensibly called Pinback (one of the bleak gags in the film is that the astronauts have all been in space so long they have forgotten their own first names, and can perhaps only remember their surnames because they are stencilled on the front of their overalls), but at one point, in a rather poignant video diary sequence (and that's pretty prescient for 1972), he claims that he is a victim of mistaken identity, and is in fact a lowly member of the ground crew called Bill Froog who has come on the mission by mistake - "Sgt Pinback's uniforms do not fit me. The underwear is too loose."
The secret alias of a fictional character in an obscure cult film makes an appealing nom de guerre, I feel.
Some years ago, I was browsing in a bookshop in New York - Coliseum Books, in its old location just off Columbus Circle (it has since moved to much airier, but far less characterful, premises in Midtown, just over the road from the New York Public Library) - when I happened upon a book (on the 'How To Write A Screenplay' shelf, I believe) written by one William Froug. He had been a professor of film studies in the 60s and 70s - at UCLA, possibly; I forget. So, it seems very possible that Carpenter and/or O'Bannon were surreptitiously paying homage to a favourite teacher. And it would appear that I have been misspelling my favourite alias all these years. Ah well - I'm too set in my ways to change now.