The Batman and Joker 2-Pack Geeki Tikis® mug set is based on the classic episode Surf’s Up! Joker’s Under!, which originally aired back on November 16, 1967. The Batman & Joker Ceramic Geeki Tikis® hold 22-26 ounces of your favorite beverage. Each Geeki Tikis® mug features beautiful sculpted detailing true to the character it is paying homage to. These ceramic mugs are high-quality, microwave and dishwasher safe.