Flying Pig I #225 - Funny Humor Ceramic 11oz Color Changing Coffee Mug Cup Mug appears black. Add hot liquid and reveal the print! Changes Color! Just Add Hot Water! Safe For The Microwave. Not Dishwasher Safe. Ceramic 11oz Black Color Changing Coffee Mug When the mug is empty and/or does not have any liquid in it over room temperature the mug will appear black as shown. For the mug to transform and show the image simply add any hot liquid of your choice. We prefer coffee, because we need to stay caffeinated to make these awesome designs, but you can add anything you like! The moment hot liquid hits the bottom of the mug your image will start to display as shown. Once your mug is full to the top with your favorite liquid you now see the awesome full design. Enjoy your drink and the view!