The first step toward warding off these Vince Vaughn and Owen Wilson wannabes is to know how to identify the culprits. Since this is Cvent's second year holding a large-scale conference in Las Vegas – and Vegas is packed with vacationers looking for a good time – we're well versed in spotting and tactfully redirecting crashers. Here are a few tips for recognizing the seven types you will meet at conferences and here are some simple ways to stop crashers in their tracks: