Surely a parody?

I was listening to the radio in the car earlier when a song came on that I could have sworn was a Flight of the Conchords-style spoof... The opening lyric was:

"If I had eyes in the back of my head I'd have told you that you looked good as I walked away"

But no, apparently it is a genuine song by Jack Johnson. How did he manage to achieve something so close to parody? How does he sing it with a straight face???

(by-the-by: if you're not already into FotC, what have you been doing??)