I’d not heard of this. It’s Gaelic for ‘women’s Christmas’, traditionally falling on the 6th January – the feast of the Epiphany – when, after working hard for others through the rest of the Christmas season, women had some time for themselves:
“In rural and small-town Catholic Ireland, especially, women would gather in each other’s homes or local pubs for a few stolen hours of gaiety while the men looked after the brood.
Speaking to the Times, Irish scholar Alan Titley remarked that the tradition was most common in the west of Ireland in a litany of different ways. “Most women in west Kerry would have raised five or six turkeys for sale at the Christmas market,” he said. “They kept the money – like egg money – and if there was anything left over after Christmas they spent it on themselves.”