Because really, when she sings this? It’s pretty much impossible to stay in a bad mood.
http://www.youtube.com/watch?v=y6Vpmz4BVU8

* I know most of y’all will probably not watch the video because it’s over 3 minutes long, but you should really listen to the last 10 seconds or so, just to hear the way she pronounces “Thumbkin.” Her “Th” sounds like an “F,” and she doesn’t enunciate the M. So it sounds… well, it sounds like something that should be bleeped, let’s put it that way.