The first time I've been on an airplane was when I was about 8 months old (when we moved to the Middle East). Ever since then, we took vacations out of the country every summer (mostly, back to our home country). And each trip takes 16 hours by plane. So naturally, you're either going to want to piss or poop sometime within that time frame. And personally, I've actually hated having to do so. Aside from the fact that I have to stick my butt into someone else's face just to get out of my seat (since I love sitting by the window), the toilet flush is pretty flippin' scary.
Oh gawd. Just look at it, mocking me. LOOK.AT.IT.