In trying to define what makes certain music "funky," it's best to not get too scientific. Aficionados will deride a rhythm section for not being "in the pocket" or opine loudly about the merits of a particular groove, but these are often subjective observations. The best funk music doesn't adhere to a strict code; it breaks rules and makes new ones. It's hard to think of a bigger post-James Brown game-changer than George Clinton, who headlines the St. Louis Super Music Fest. His P-Funk outfits summoned a musical apocalypse in divergent ways: Funkadelic through hard rocking, end-of-days paranoia and Parliament through party-starting electro-funk. Clinton headlines the festival alongside fellow funk trailblazers Zapp, Teena Marie and Cameo.