reverse flush
The result of making a large, forceful, and explosive deposit into a toilet, causing the water in the bowl to splash back on your ass.
That king-sized chimichanga from The Alamo had me doing the reverse flush the minute I got home.
Reverse Courtesy Flush
When you find someone else's shit in the toilet and you have to flush before you use it
I got into the stall at the restaurant and had to do a reverse courtesy flush for the guy before me before I could drop my own deuce.