trap door shit
A violent shit best described as simulating the act the free-fall that is possible should one kick open a "trap door" and fall through - a "trap door shit" is when a defecator victoriously evacuates with JUST enough time before shitting oneself - that unrelenting shit being of flood force when released - kicking out as if it was free falling through a "trap door." Often, but not always triggered by diarrhea.
"It was a real race to the toilet - I was fighting hard to hold in a trap door shit that was screaming and threatening to run down my leg."