[thedoc (OP)]

John Gamel asked the Naked Scientists:
   
Chris, here's a good question for your show, which I title "The Reliable Rectum." As we all know, when we get the urge to discharge material from our "back doors," we can almost always sense (with rare but disastrous exceptions) whether the material is a gas, a liquid, or solid matter. How does our rectum perform this marvelous feat?



What do you think?