In the UK - what does "cheeky half" mean?

And what is the expression's origin?

(I believe it's related to beer)


Literally it means half a pint, when perhaps you shouldn't be drinking, for example, at lunchtime when you still have an afternoon of work left. Though it may be that if someone says they're 'just going for a cheeky half', they actually mean they are intending to consume rather a lot more than that.

Half a pint