Klunk 

It means poop.
The reason it's called that is because it's the sound that poop makes when it lands in the water.
(Definition from maze runner)

"You look like a pile of klunk!"

Klunk by Cold Mafia August 1, 2014

Klunk 

The sound made by a metaphorical lead balloon as it lands on the ground symbolising the way in which an unfunny joke has gone down.

Knock Knock
Who's There
Doctor
Doctor Who
Exactly
Klunk !

Klunk by Bunter October 13, 2004

Klunk 

When you shit in a vase and it makes a clunking sound.

*klunk* I just shat in a vase :)

Klunk by Sex Offender with a Penis August 30, 2018

Klunk 

(vb) to swallow, verb derived from Cornish language and survived into dialect.

Klunk'n down, pard!

Klunk by Matthi Glas January 10, 2020

klunk 

the feeling of belatedness one has when they've eaten too much

That extra slice of cake gave me lots of klunk.

klunk by teenbishkokie May 2, 2021

klunk hat 

To push your balls up into the eye sockets of a woman while slapping your dick over the bridge of her nose.

Sally, I'm gonna give you a nice klunk hat after dinner.

klunk hat by Scott March 5, 2005

Klunk dump

Literally shitting bricks.

Holy crap dude someone scared me and i took a klunk dump.
Oh shoot dude.

Klunk dump by 420 yes scope March 20, 2017