I wonder why we use the expression ‘I don’t care a fig’ to express a lack of interest in something. The fig is one of the most extraordinary fruits around. It’s nutritious, beautiful to look at whether green and plump or glistening and black, exquisite fresh or dried, thirst-quenching, luxurious. Sexy. Slightly alien with its sugary tendrils clustered inside the skin. Just look at this one, fresh and bursting open on Daniela’s table in Norma.
CHARLES LAMBERT 
I’m not sure either. I know this isn’t the real origin, but Buddha supposedly reached enlightenment while sitting beneath a bodhi tree which is basically a fig tree. I assume it came about because figs were rather common, but I guess I don’t given enough of a fig to find out for sure.
My Dictionary of Historical Slang tells me that a fig was a contemptuous Spanish gesture in which the thumb was thrust forward between the two first fingers. I can’t help thinking that this was an obscene gesture, so it doesn’t exactly topple the assumption I’ve always had which was that ‘fig’ was a euphemism for the other f-word. Alternatively, ‘fig’ is most definitely a euphemism for vagina, so maybe…