I picked up a vinyl copy of the Dr. John album "Destively Bonnaroo" just for the cover art/Bonnaroo connection. It turned out to be an amazing album! Dr. John backed by the Meters. The Superjam last year was amazing with Dr. John, Mike et al. If I remember correctly, I think there is a track called Destively Bonnaroo on the album and I was really waiting for them to play it. Although I didn't catch the whole set, they didn 't play it while I was there, but I'm surprised that this isn't a popular Bonnaroo cover.
I bought a copy of the album on ebay a month ago; still in the shrink wrap. I don't have a turntable anymore, but I'm looking forward to hearing the record eventually.
Bonnaroo comes from the whole New Orleans thing...I don't know if the proper description is to say it's Cajun or Creole or what...and desitively is really not a derivative of desitive, I don't think. It's just a word play on "definitely/positively," or put another way, absolutely. So "Desitively Bonnaroo" is just another way of saying "completely off the hook."
By the way, the Bonnaroo sticker I made for the first year simply said: "desitively bonnaroo," in lower case black font on white vinyl. Nobody had a freaking clue...