Flushing the toilet, as not to clog it if your taking a big crap
-- Used if you are taking such a big crap that it might clog the toilet, so you flush 1/2 way.
Man, give that thing a mercy flush, so it wont overflow!
The extra flush that comes between wiping and dumping, used when the shit is unusually large to prevent a plug of soggy TP and feces forming in the pipes.
"Shit guys, I took the biggest crap yesterday, I had to mercy flush so the toilet wouldn't plug!"
Flushing a particularaly bad-smelling turd down the toilet in the stall of a public bathroom while you are still crapping so other people will not smell it. This can be repeated as many times as necessary.
Person in right stall: *Poops*
Person in left stall: "Oh God! That's Horrible! How about a
Person in right stall: *Flushes*
Person in left stall: "Thanks."
Person in right stall: "Welcome" *Continues Pooping*
when a dump smells so bad that you must flush half-way through for your own or the person in the next cubicle's health
omg this dump stinks, i better mercy flush
When you flush a dying fish down the toilet so he can have 'one last ride'
Ooh it looks like Goldy's headed for the big ocean in the sky...better give him a mercy flush.
When Gary's shit smells so bad that he should flush the toilet before the turd even came out.