Wacky Races Wacky Muttley Morphing Heat Sensitive Mug For fans of the old Wacky Races and the new this super bright mug features Muttley the dog and his most famous quote Heheheheh The exterior of this 11oz mug transforms from black as hot liquid is added revealing the hidden image in full vivid colors Features . Color changing heat sensitive ceramic mug. Heat activation reveals hidden image. Designed and printed in the USA. Authentic Morphing Mugs heat sensitive mug Specifications . Capacity 11 oz. Subject Wackey Muttley