13 Heat-Activated Mugs

Heat-activated mugs are fun and easy ways to tell whether the cup of coffee has been sitting out for a minute too long. It's easy to get distracted from the morning cup of coffee and, upon return to the supposedly delightful caffeine, a mouthful of room temperature coffee is sipped, leaving an unpleasant aftertaste. With heat-activated mugs, the images change on the exterior, letting users know how hot, warm or cold the coffee or tea has become.

The cute coffee cups range from nerdy pixelated hearts to heat-sensitive fuel bars and mood-changing faces to arcade-inspired designs. Each cup has its own quirky way of letting people know when it's time to dump out the lukewarm drink and pour a new one, including (dis)appearing images and fading health bars.