A video has been making the rounds of an airline pilot revealing where your poop goes after you flush. Most people think it dumps directly down into a waste area below, but that's not exactly the case.
It goes through a plumbing system to the back of the plane, and into a sealed compartment for the ground crew to remove. He adds that a long-haul flight will have over 1,000 flushes, and create over 320 gallons of waste.
(Here's the video. Afraid of flying? In this clip he says you have a one-in-3.37 billion chance of dying in a plane accident . . . which he compares to a one-in-three million chance of dying if you get food poisoning.)