Lol. I’ve juggled non-buoyant, air filled balloons but because of their elasticity they don’t exactly settle into your hand when they land.

In my juggling routine, one of the things I do is transition to lying on my back face up while continuing to juggle. I’m throwing the balls straight up above my head while lying perfectly flat, which feels pretty weird. So I can’t imagine how difficult it would be to be physically upside down while juggling.