The plane toilet is a mysterious contraption. Unlike its grounded cousins, it is far louder when it flushes, complete with a giant woosh of air that will freak out the uninitiated. If you've ever been curious as to how plane toilets actually function in the air, the cheery engineers in "The Pee Lab" (seriously) over at Air New Zealand have put together a behind-the-scenes video explainer. You'll find out that planes don't go releasing toilet waste in the sky and onto people's heads, and that a single toilet costs US$17,000. That's likely the most expensive receptacle you'll ever have the pleasure of doing your business in, by the way. Anyway, don't just take our word for it -- let these Kiwis show how excited they are about fixing toilets. [h/tNZ Herald] Have something to add to this story? Share it in the comments.