I really have no idea how this started. My dad and I are going around calling each other random things. When he comes home from work he'll stick his head into my room and say something like, "You're an undercooked steak." to which I respond, "Oh yeah, well you're a wrinkled pillowcase!"
And at random we just go around calling each other these silly names. It's so funny. I think the last thing I called him was "an unwound watch". Now he has to think of something really creative to get back at me. Sometimes if I get him real good he'll go to my mom and go "Cyndi called me a..." and they laugh.
Now I'm giggling just thinking about it.