Green’s Dictionary of Slang

Nescafé n.

[the gesture, based on the shaking of a jar of coffee, imitates that of male masturbation and thus means wanker n. (2); ? also rhy. sl. Gareth Hunt (the star of the Nescafé adverts who shook the coffee) = cunt n. (4)]

a hand gesture used to indicate one’s contempt.

Show quotations
[UK]Guardian G2 9 July 18: I never knew what ‘Nescafé’ means [...] Remember the old advert with Gareth Hunt shaking coffee beans in his fist? Now do that out of your car window – that’s it, you’re giving a Nescafé.