This coffee mug will be sure impress your co-workers. Dazzle them all as they watch you fill up your cup with hot java, changing the average-looking “COLD” black mug into a white “HOT” one. The heat sensitive pigment on this mug will keep your boss wondering if anyone is getting work done with the huddle around your desk. Also a great way to visually tell if you could use a warm-up. Surprisingly, it is dishwasher safe too.