A dog tricks a puppy
A puppy wants to play with another dog. He runs on a path dug in the snow like a circle. The dog had the good idea to do one rotation to make believe to the puppy he is always running inside. The puppy did saw the trick, he continues to run thinking to be followed by the dog until he saw the other dog out of the circle looking at him.
Fortunately for the puppy, his handler runs to the circle too.