Gary Clark Jr. lived up to the title of his song "Ain't Messin 'Round" last night on Jimmy Kimmel Live, where the Texas bluesman blew through the gutty tune shortly after announcing the inaugural year of his own Maverick Music Festival in San Antonio. Buttoned up in a double-breasted coat with a longshoreman's cap perched on the back of his head, Clark churned out the gritty riff on a big red guitar while his band filled in the sound around him. He stayed afterward to perform another tune, "Numb," which is also from his latest album Blak and Blu.