You can never have too much Pac-Man in your life. Or Space Invaders. Excuse me, “Pac Boy” and “Space Intruders”. You could buy yourself a regular mug featuring arcade scenes, but these mugs from Thinkgeek react to the heat in your drink and actually do things.
For instance the Pac Boy mug starts off with an empty maze, but when you add heat and it gets filled with detail. Same with the Space Intruders mug.