Mount Pooji
Like the Japanese mountain that has much of its base below water with only it's crest visible on land, Mount Pooji is when you take such a huge shit that it fills the entire bowl below the waterline and breaches the water like a majestic orca.
Jack: Sam what in holy hell did you do to my toilet, there was shit everywhere.
Sam: Made a Mount Pooji. You're welcome.
Sam: Made a Mount Pooji. You're welcome.