As the guys wrapped up their series on time travel, listeners asked to hear more about the mysterious John Titor. Who was (or is) he? Did he really travel through time? Some people believe his story, while others are convinced that it's nothing more than an internet hoax -- and a debunked one, at that. Tune in to this Stuff They Don't Want You To Know video to learn more -- and to hear if your listener mail or tweet made it on the air.