1980s in juvenile usage, a person who would rather eat bread than have sex.
From a 1980's advertising campaign for bread in Australia: A man turns down an evening with a buxom wench to repair with a slice of multigrain. Voiceover: "Man does not live by bread alone but with Bornhoffen he comes close."
This was then contracted into "B'hoffen" with aspirated first syllable and finally just "boffin" to describe nerds.
Look at that bornhoffen, what a nerd.