What the grandfather said in the Irish?

I may regret this, but is there anyone who knows what the old man's grandfather or great-grandfather, whatever, shouted in the Irish when he was beating up the schoolteacher? I remember Fiona's grandma scolded her husband for repeating it as he told the story, even though Fiona didn't have any Irish. I'm just immature enough to want to know what he said. ;)