Laddie-o, laddie-o, laddie-o, ah, my knees must grow

The story:

I was looking through a couple old mix-CDs, hoping to find a classic or two to take with me on a long journey when my eyes landed on this one. It triggered a few fond memories of my long-gone youth, so I put it on and gleefully sang along. It was the morning after St. Patrick's Day, it all made perfect sense.
Then the Guinness left my bloodstream and I looked up the lyrics. That much for knobbly-kneed Leprechauns...