I have a cat that I swear had to have been a dog in her past life. She wants to play fetch non-stop. We can throw two balls and she'll go get both into her mouth and bring them back and put them back in our hand. She's so obsessed that we have to keep the balls in a drawer locked away. When we put them away she will spend a day digging underneath everything looking for them. And we can leave them there for months but if someone opens that drawer she will hear it from across the whole house and come running. Then the whole thing starts over.