Thunder Valley Casino Resort hosted Big & Rich and Gretchen Wilson this Friday night in their outdoor amphitheater. It was a perfect summer night for an outdoor show. Both the performers and the audience fulfilled expectations. The Musik Mafia, as they call themselves, rocked a full house on Friday night. “Sitting on your ass is extremely prohibited throughout the entire Xtreme Musik Show,” spoke an electronically-enhanced voice that served as a flight attendant style introduction to the concert. John Rich seemed to lead the performance, the likely choice considering his successful stint on Celebrity Apprentice. Big Kenny sported his usual top hat. His fringed vest and snug pinstriped pa