Short answer: who knows?
I've read in a few places that the fast version was the original concept for the song, and the slow version came second. I've also read that the "stomp stomp clap" is where the song originally came from, and it was only re-worked into the fast version because the band wanted to open shows with it, but didn't like the pace of the slow version.
"Do you think I should keep this mustache? Did you say no? F--- off."