Happy St. Patrick's Day! Glen Hansard likes to end his concerts with this, and have other musicians and guests (not all of them singers) sing a verse. It's a neat, rousing and inclusive way to end the evening. (Here's some background on the song. The lyrics can vary considerably, and it's not unusual for performers to write new verses.)
I've featured some of my favorite Irish tunes in previous years. Feel free to link any of yours in the comments.