What would you call this genre of music?

I really like music like this:

Misery - Green Day http://www.youtube.com/watch?v=JeGs9O7C3IM

Hot Volcano - Pearl and the Beard http://www.youtube.com/watch?feature=player_detailpage&v=JfwxGTvOzf4#t=60s

Is it just a slow Polka or is there a specific genre?