I forgot to say that the old man I was céilidh-ing with spoke with a barróg.
The ''Concise Oxford Dictionary of English Etymology'' doesn't give a derivation for this type of 'brogue', as opposed to the brogue from 'bróg' for a shoe; except to suggest that perhaps brogue as an accent is related to the preceding word brogue as a shoe 'in playful allusion to the foot-gear of Ir. or Sc. speakers.' Playful, my foot! A more likely, though hardly flattering, derivation is 'barróg cainte', a speech impediment!
The Irish word for an accent is 'blas' and if someone speaks with a 'blas na Mumhan', in the Munster dialect, s/he will put the stress on the second syllable of 'barróg' so it does sound rather like 'brogue'

The website from which D Ó Muirithe was quoted in message 2 of this thread, contains a novel (to me) suggestion about the origin of bunny rabbit and buns for buttocks. The big OED and the concise dict. of Etymology, just say the origin of the term bun or bunny for a rabbit is unknown. The 'novel' suggestion is that rabbits are called bunny's because they flash their white behinds as the run off, and that 'bun' for a buttock comes from the Gaelic. Well, usually for that type of bottom, we use the word 'tón' or 'tóin'. Although a naughty English phrase is translated as 'Póg mo thóin', there is nothing offensive about the word and if anyone says to you, 'Bí i do shuí ar do thóin', s/he is just saying 'sit down.' The word 'bun' is used for other types of bottoms; a base, a pedestal, a beginning. - more likely your feet than your rump, as in 'bun os cionn', 'upside down' or head over heels'. It's not at all impossible that some Gaelic speakers somewhere have used 'bun' in the way most use 'tón', and I did find a term 'bun-abhas', meaning 'rump' in Dwelly's Gaelic dictionary. But I haven't come across any bunny-like Irish or Scottish Gaelic word for a rabbit. The Irish for a rabbit is cóinín, related to 'coney' in English.

Can anyone tell me when 'buttocks' started being called 'buns'. I think the latter is an American slang term and I think it's relatively recent; I certainly didn't hear it as I was growing up. I never intuitively related the term to bunny rabbits, even Playboy bunnies. Rather I thought first of the sound being similar to the word 'bum' and then as the buttocks being shaped something like bread buns (like baps or blaghs in Ireland). And I would think that 'bum' is a contraction of 'bottom', though the ''Concise Oxford Dictionary of Etymology'' states that the word, 'bom' on Middle English, is of 'unknown origin'.
For 'bottom', on the other hand (or foot) it gives Old English 'botm' and 'bodan' back to Indo-European bhudhme (hence Latin 'fundus', Sanskrit 'budhna' - I imagine the Gaelic word 'bun' also has this derivation in common with the English word 'bottom').