Tectonic Shit
When you have a shit ready to exit a person's colon, but waited too long. The shit starts traveling back up the colon to start hibernation, but it is met with a new shit ready to blow out. The turds collide in the intestine and start to overlap just like tectonic plates.
John: "Karl, where have you been all day?'
Karl: " I somehow managed to pass a tectonic Shit and not die"
Karl: " I somehow managed to pass a tectonic Shit and not die"