I'll get this out of the way, I'm a sucker for balloon experiments; there's a surprising amount of variety in the simple idea of gasses and liquids in an expandable container.

So when Astronaut Don Pettit showed his water balloon experiments within the vacuum of space, I was understandably riveted at the effects. In all honesty, the hovering water effect was pretty predictable while remaining interesting and rather hypnotic. The compelling balloon experiment was accomplished while Pettit was stationed on the International Space Station, presumably while he was on break, not doing important space station stuff.

That brings me to another question. How come Pettit can bring a pocket knife onto the International Space Station, but I can't bring a bottle of water onto an airplane?