The sound of your brain collapsing when something too confusing or too mind blowingly awesome is said to you. If your brain was a building, kathunk would be this building suddenly falling to shambles. Beware! Many never recover.
Shannon: The reason Einstein postulates that an objects length can change with its speed is due to its rotation in the 4 dimensional space time continuum. Any thoughts?
Sarah: Shannon! A wild goat just kicked Santi in the nads!
Sarah: I know, right?
1. Noun: The sound created by human shit hitting the water in a toilet. Often as a direct result of how large the log was and how deep the bowl is.
2. Verb: The action that brests perform when a topless female is getting fucked missionary.
1. Man, I had to hang on with both hands to try and and squelch that last kathunk.
2. I felt like I was going to break that bitches nose, you see how those things were kathunking her head?