Jim Henson Fraggle Rock Doozers at Work Coffee Mug Caution: Doozers at work! This Fraggle Rock Doozers At Work Black Ceramic Mug is the perfect thing for fans of the Fraggle Rock series. The mug features an image of a Doozer that states, 'Doozers at work.' Holds 11 ounces. Hand wash only. Not dishwasher safe. Ages 14 and up.