Everyone has some form of tradition that is passed though generations of families, most of which we never bothering exploring.
Favorite Irish drinks - "When in Rome ..." applies to any place in the world, really. Especially when it comes to food and drink. True, you can survive an Irish holiday on Big Macs and Coke (or Whoppers and Pepsi, for the sake of variety). But will you really have experienced the local cuisine? No - and going into a pub and drinking just Bud Light should be positively discouraged. If you want to down a few, why not try the local brew?
Nollaig Shona Dhuit is Merry Christmas in Irish Gaelic, which is still taught in schools in Eire, the Irish Republic. Northern Ireland is part of the United Kingdom. Christmas in Ireland is a traditional holiday in both parts of the island, and very much a family and religious celebration!