When you don’t quite make it to the bowl with your liquid poop and it ends up on the seat. In a hurry you then sit on the seat and this the diarrhea.
Dude, I ate too much velveeta cheese and hormel chili last night and it gave me tummy problems. I ran like Flojo to the bathroom and diarrhea’d the seat. Now my thighs are all chafed from the poo pants I had to wear all day at work.