I would do one, and then I would help him do one, and we would laugh and applaud ourselves and then do it over and over again.
And then this weekend, Ben started to assume the position on his own! The first time he did it, it was right next to the sharp corner of our fireplace (literally the only exposed sharp corner in our house, I think). So, I suppose we will now be on the lookout for spontaneous gymnastics moves in dangerous areas.
But here he is trying it in his somersault-safe bedroom: