19. One, two, three

In pairs, face each other.
Start counting from one to three between yourselves, over and over.  Next stage!
Instead of saying the number "one", you should clap your hands, but you would still say "two" and three" aloud.
The next step is that instead of saying "three", you should put up your right hand.
The final step is that instead of saying "two" you should bend your knees