Define Fancy A Bum Meaning

When a guy asks another guy "do you fancy a bum?" he wants to know if he's into some man on man action.

Same as 'fancy ass sex'.

When someone asks 'fancy a bum', it can often be translated as 'fancy a cuppa'. However caution should be used when using this term with people who are unfamiliar with the phrase.

Often used in the work place.

A question to colleagues or friends (mainly in a work/office environment) when you are gasping for a cup of tea and want to go to the kitchen in a group to get drinks and socialise.