Abstract: A dummy includes a hollow nipple member and a ring member including a ring with an insert rod to be inserted into the hollow nipple to secure the nipple member and the ring member together to form a dummy. The insert rod includes a plurality of knurls, each two adjacent knurls having a recess therebetween. Due to the provision of the recesses between the knurls, the gums of the baby can be advantageously massaged and the molars of the baby can be effectively ground.