Meg & Tera occasionally get into the bathtub. The shower curtain closes off most of it, so when they're in there, the way out for them isn't necessarily obvious. As a result, they do what kittens do best -- running around in circles. Very fast and very circular.
At one point, Meg leapt into the bathtub while Tera was occupied by the food dish. She decided now was a good time for some of that tail-chasing action and spun round twice before falling down. Then she got up and did exactly the same thing.
I wouldn't necessarily accuse them of being the _smartest_ kittens in the world. But damn, are they ever cute ; )