Explanation. There's a show on the Disney Channel called Imagination Movers. Awesome show! They recently televised a concert and during one of the songs they hula. You can hear the song in the background if you have your volume up. We really only watched the concert once or twice, but this song was also in a commercial during one of the movies we recorded that Austin loves to watch. So he's seen this commercial lots of times.
Randomly one day, he jumps off the couch and starts dancing and singing along! I had never even paid attention to the song, let alone pushed him to start hula-ing along with it. Totally his idea! Of course, I did encourage him to do it over and over again, to show Daddy and other visitors, and of course to get it on video!
His hula skills may need a little work, but he's not too shabby for having no formal training. =P