Don't let the Daleks know that hot water makes the Doctor disappear
You probably think that police box on the side of your mug is just some weird garden shed built by a neighbor. Then, when you fill your mug with hot liquid that police box disappears and you realize that it's actually the Doctor's TARDIS. He probably just saved the planet from invading space lobsters with a giant hot butter gun, but you'll never know. This 3-1/2" ceramic mug shows the TARDIS on an English street, but when it's filled with hot liquid, the TARDIS transports into deep space (way over on the other side of the mug!). As the liquid cools, the TARDIS will return. You know, because of Cybermen.