The Fruit and Nut is one of two symptoms of the materialistic 21st Century world in which we find ourselves:
1) The first is Cadbury's Fruit and Nut, a delicious chocolate bar beloved the world around for its high quality but never stingy helping of raisins and peanuts, sure to cure any ails modern life can throw at you.
2) The second is a crude sex act, believed to have originated in South Wales. The act requires very specific conditions for it to count: it is initiated at first by a devil's three way (a threesome where two men double penetrate a woman) during a time when the lady is on her period and simultaneously defecating herself. After a while the men pull out, the woman flips around and the men enter in again.
When the men have received both the 'fruit' and the 'nut' the act is complete and all 3 participants are free to try and resume their normal lives.
Guy 1: "Dude! We should totally give Sandy the Fruit and Nut tonight!"
Guy 2: "Yeah, just make sure our balls don't touch!"