GMs definitely need to enforce strict "in character" play, eliminate "across the table" chatter, and by doing so - set the scene for an awesome role-play experience!
A man was killed somehow and brought back to life. He, uniquely, remembers everything about Death, from the skeleton on the horse that guided him, to the afterlife itself. And the annoying bit where he was wrenched from his jacuzzi. He now has penned the instant best seller, entitled 'To Death and Back: My adventurers beyond the grave.' OR IS IT? Is this man telling the truth, or simply a very good liar? Is it all a fraud?