I have. In fact, I think I discovered it :P. I don't know if that is true though.

Anyway, all you do is add a tweedle boss (or any other boss of that matter, I just chose tweedle because it is invisible) and plop a robot boss devan somewhere. What happens is that a weird jazz boss appears. It shoots out other jazzes when you hit it and floods your screen with even more when killed. The only problem is it dissapears when you go near it.