When pooping in a public restroom stall, this is any individual that is also pooping in an adjacent stall, either on the left or right or both. Having one or more Pooping Partners is generally undesired as you are often subjected to your Pooping Partner's loud grunts, snorts, and flatulence as well as having to deal with the smells of your own defecation mingling with theirs.
I hate having pooping partners. Took me 30 to find a bathroom with only one stall.
My pooping partner today almost gassed me out. Couldn't breathe for my entire shit session.
I heard my pooping partner grunt like a dying goat.