When your poop is so big it sticks halfway out of the water, like the famous photograph of the Loch Ness Monster
Yo, Harold! Come check out the size of this Messy Nessy before I flush!
by Turd_Burgler December 8, 2017
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(noun)- a turd of mythical size. The base stays hidden in the bowl, while the head is the only thing that is seen. If you do not snap a picture of it....people may never believe it happened.

In addition to its length, circumference, and overall gargantuan stature, these often become what are also known as "bowl stainers." Leaving behind a mess that...well...isn't human.
Brother: Dude, I just took a two foot bowl stainer and no one was home to see it.

Other brother: I don't believe you.

Brother: Damn! Another Loch Nessie Messie....
by Lat 5 July 31, 2011
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When your homie smells like 3 day old bong water.
"Damn, Sharon over there smells like a hot messy nessy!"
by WeeedBear July 29, 2021
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