Dumbening 

A rare, genetic condition found in males, usually surfacing at the on-set of puberty; the result of which is a swift plummeting of the carrier's overall intelligence.

Young Abraham quickly went from smart as a monkey to dumb as a chimp, as a result of his dumbening.

Dumbening by Michael T. Lynch Jr., Scientician October 12, 2003

Dummenting 

Dumb+comment= Dumment

When someone says something out of their league,not cool, something DUMB
..they are dummenting

*Texting*
Griz- You are talking out of your league bruh! Your channel is too small to post stuff like that.

Blake- Dude, your channel is even smaller why even bother?

Griz- I said your content was not for small YouTubers like you ! I post stuff of my own class STOP DUMMENTING!!!

Dummenting by Emporiohak March 7, 2018

Dumbest Common Denominator 

The most logically-challenged portion of the general population for which the most obvious warnings, posts, signs and instructions must be written or designed to avoid catastrophe.

On the lid of the coffee cup: Contents may be hot.
On a package of kitchen knives: Caution! Items are sharp.
On a trash bag: Do not place over head.
At a railroad crossing: No parking.
On a clothes dryer: Do not place children or animals inside.

"This is the dumbest sign I've ever seen. Do they think I'm a complete moron?"

"Dude. Gotta plan for the Dumbest Common Denominator."

Dumbest Common Denominator by Upallnightagain September 25, 2011

dumbest place on earth

Youtube comments section.

A: I just read that youtube comment and felt like my IQ dropped by like 10 points.
B: Youtube comments section is literally the dumbest place on earth. I'd suggest you read pornhub comments instead.
...
A: Thanks man, that was really helpful advice.

dumbest place on earth by rjlovesu June 23, 2020

fuckest dumbest 

drunk talk for - Fucking Dumbest

Late night at a strip club, after a few drinks....

Chody: "Dude what if your sister quit college to become a stripper here?"

Fat Cobe: "Man, I would beat her ass"

Chody: "Yeah, that would be the fuckest dumbest thing she ever did"

Fat Cobe: "Did you just say fuckest dumbest?"

Chody: "Hahaha, yeah I did, I meant fucking dumbest"

fuckest dumbest by niggerama January 27, 2008

dumbmentia 

A disorder of the brain caused by a chronic state of bad choices, dumb decisions, and general assholery that gets worse with age.

My ex has dumbmentia.

dumbmentia by AmyChristine March 23, 2021

dumbest rhino 

a juvenile rhino that is incredibly stupid. It has a distictive call and dress sense. it tends to wear burton clothing.

The dumbest rhino call is: MOOOOOOOOO!

dumbest rhino by Golden Jewberwilly May 9, 2003