“The worst offense in the sing is the happy, sweet tune and the lyrics don’t include anything bad happening to the perp.”
The point is the contrast, it’s kind of like “Sunny Came Home” in that regard. The next layer of “depth”: He’s thinking about it, it’s not made clear whether or not he acts on his thoughts.
Well, it isn’t made clear in the song that he’s only thinking about it. If I didn’t see that, neither will a 15 year old troubled boy.