Poopetual motion
Describes the act of poop moving continuously, specifically moving between 2 or more buttholes; when a person poops into another person's butthole, and then that 2nd person poops into the 1st person's butthole, and then the 1st person poops into the 2nd's butt again (effectively re-pooping their own poop for a 2nd time, plus whatever additional poop the 2nd person had pooped) and the cycle repeats; commonly known as "pooping back and forth"
In middle school, my friend Casey & I watched a video on the internet of 2 friends pooping back & forth, inspiring us to pull our own pants down & create some "Poopetual motion" for ourselves.