OK. Here's the one you've been waiting for...

How do you go to the bathroom in space?
-- Luke (Team Space Shuttle)

MAGNUS: Actually this is a very interesting engineering problem when you think about it. What happens on Earth when you go to the bathroom? Well, gravity turns out to be very helpful since it makes everything fall away from you into the toilet bowl. Imagine what would happen if there was no gravity assist! So when the engineers had to think of how to build a toilet for space, they needed some other way to move the urine and feces away and into storage tanks. It turns out the airflow does a good job as a transport method, so they designed a toilet that kind of works like a vacuum cleaner. When you go to the toilet in space, whether on the shuttle or the ISS, one of the first things you do is turn on a fan that starts up an airflow through the hose that you will urinate in. The airflow moves the urine "away" and through the processing facilities and into the storage tank. For defecation it is the same thing. You start a fan, make a good seal with your butt, and the air flow helps send things to where they need to go for storage. It works really well!