Nanny Faye went down under for a show she'll never quite forget.  Well, she didn't quite make it all the way to Australia, but the matriarch of the Chrisley family and her grandson Chase Chrisley were surrounded by muscular Australian men when they sat down at Las Vegas' famed Thunder from Down Under show at Excalibur Hotel and Casino.  In an exclusive clip from this week's episode of Chrisley Knows Best, the entire family is shown in Sin City in honor of Savannah Chrisley's Miss Teen USA competition. While his sister and parents are preoccupied with pageant prep, Chase decided to bring grandma to the show of a lifetime.  "If my grandma wants to see...