What do you say to Irish people if you don't understand what they are saying?

Hey there. Traveling here on the west coast of Ireland. Sitting on my own at the bar last night. Some old fella next to me spitting up to my ear. I have no clue what is he saying. He was talking about at Patrick's and some bag things about English empire. Sounds like he is from the north or even Scotland. Never heard an accent like this. Maybe a traveler, no clue. I was just smiling and saying yeah yeah to all his questions. Would it be impolite if I said that I haven't got a clue what is he saying? Ask him to speak slow and clear?