ROYAL OAK, MI—Despite last-minute fears of a concert cancellation due to transportation problems—as well as the fact that it was a school night—Violent J and Shaggy 2 Dope, the shock-rock rappers known as Insane Clown Posse, managed to make it to their Monday performance at Detroit's Joe Louis Arena after securing a ride from 2 Dope's mom. Above: Insane Clown Posse members Violent J and Shaggy 2 Dope. "Man, we were so worried we wouldn't be able to get to the concert," J told several social-studies classmates Tuesday. "That would've sucked big-time, because we'd been looking forward to it...