Thing One and Thing Two

 My son is a sturdy boy. His interests include tae kwon do and fencing.  He has a green belt in the former.  Being a young martial artist has given him rather big biceps for a 10-year-old.  He's very proud of them.  He's named them "Thing One" and "Thing Two" after the troublemakers in The Cat in the Hat. 

He was introducing  "Thing One" and "Thing Two" to his friend. His friend starts playing with the fleshy parts of his own arms and says, "This is Thing Three and Thing Four."

I couldn't clearly see  what they were doing, but the banter continued, each of them pointing to something (perhaps a body part) and calling it "Thing Five", "Thing Six", and so on.