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'.
- Hey mate, what a nice day.
- Do you fancy a bum?
- I beg your pardon?
- Yeah, you and me, getting some.
by Fabilicious March 11, 2008
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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.
Chris: Ayup Tom, just got out of a long meeting and really fancy a bum.
by iBeech October 8, 2014
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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.
Tom - "I'm quite thirsty."
Chris - "Fancy a bum?"
Tom - "I'd love a bum. Put the kettle on and I'll meet you in the kitchen."
by megaduff October 8, 2014
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