poop pendulum
"Poop pendulums" occur when one takes a very large and long shit that hangs from the rectum for a long time. As the shitter tries to squeeze it off, the poop begins to oscillate back and forth, often resulting in "brown balls." The pendulum effect can be caused by many different scenarios, though, such on on rough sees, during earthquakes, while sextashitting, and when mastecrapping.
"Dude, Tina gave me the worse case of blue balls, so I went to mastecrap one out. I ended up with a poop pendulum and brown balls. I feel much better."