I trust I need no caveats about not following links if you're easily offended?
His humor is not my favorite style, but that said, most of the the "wow, THIS is what I'm going to remember from this Folk Festival" were his songs. His "la la la it's a great day" style song was reminiscent of the bird scene in Shrek. Then he sang a couple of songs about highways. He started with I-80 in Iowa. (Corn corn corn corn whats that smell corn corn...) Then he moved on to I-75 in Michigan. As soon as he got to one particular section (pothole a-hole pothole a-hole pothole a-hole COPS COPS COPS COPS), I didn't think anything funnier would happen that evening. I was wrong wrong wrong.
Ok... Here's one version on you-tube: http://www.youtube.com/watch?v=_-ksuOaI61g -- but that doesn't have the final, newer, verse... which is included in this: http://www.youtube.com/watch?v=HwffYU3lu0c.