This was originally an 18th-century slang term for a brothel – and as late as the 20th century in Dublin, brothel madams were known as “kip-keepers”. (Source)
There are two theories here. The most widely-held one is that it comes from gall, the Irish for an English person – which might explain the Cork usage of gowl to mean an eejit. The other theory, relating to its more obscene meaning, is that it may be from the Irish gabhal – meaning junction, fork or crotch. (Source)
3. Beor / Beure / Beoir (various spellings)
Originally from Traveller’s cant, where it simply meant ‘woman’. It’s since been corrupted to become slang for an attractive woman or girl. This 1937 guide to Shelta, the Traveller language, gives a sample sentence - Biyor a kyena krish blanóg – “The woman of the house is an old cow.” (Source)
Probably from the ancient Irish Síle na Gig, transliterated as sheela-na-gig: the carvings, often found in churches, of naked women grasping giant exaggerated versions of their naughty bits. (Bonus: “Geebag” is actually slang for a condom.)
Some believe that culchie comes from the Irish cúl an tí, meaning the back of the house – the reason being that country people traditionally often entered friends and neighbours’ houses by the back door rather than the front (which was only for formal visits).
Another possibility is that it comes from coillte, meaning the woods, to simply signify coming from a rural area (a bit like the US slang ‘the backwoods’).
Widely believed to come from the Union Jack – so basically, it’s a derogatory suggestion that Dubliners were more likely to sympathise with Britain and wave the flag. They are ‘little Jacks’. (Source)
Originally from the Irish maith meaning good. It became associated with ‘girl’ as a shortened form of maith an cailín - literally ‘good girl’, but used to mean girlfriend. Slightly unpleasantly, it’s also British slang for ‘prostitute’. (Source)
The best possible explanation for the ‘penis’ meaning of langer is that it comes from leangaire – apparently a word in a dictionary of the Muskerry Gaeltacht meaning “a long, slender salmon”. (We haven’t been able to confirm this.)
Some have suggested that its association with Cork people comes from a time in the 19th century when the Munster Fusiliers regiment of the British Army was posted to India, and were plagued by Langur monkeys in the jungles. The soldiers brought the word back with them to refer to uncouth, wild people. (Source)