Dumber than a rock 

A guy named Michael who acts like he knows everything and does stupid shit.

Michael: How do you spell "sexist"
Me: You're dumber than a rock

Dumber than a rock by 093707053 July 3, 2018

Dumbinant 

(noun) Male or Female: A wannabe Dominant in the BDSM world, easily identified and laughed at by experienced lifestylers.

A Dumbinant will pretend to know everything. A Dumbinant never takes advice. A Dumbinant thinks that dressing in leather and carrying a flogger confers automatic dominant status toward anyone who identifies as a submissive.

Dumbinant by YourToyBox January 5, 2009

dumber than dumb 

Willfully refusing to use common sense and good judgement. Taking an already poor idea and taking it to the extreme.

On Halloween, Amber Langford and Annie Collinge acting, dumber than dumb, dressed up as exploding twin towers, without sympathy to the 2,977 victims of a terrorist attack at the World Trade Center in NYC on 9/11/2001 at Rosie's Club in Chester, UK. The costumes of the two girls featured the North and South Towers with paper representing fire and smoke protruding from the buildings which where made to appear as short mini-dresses.

dumber than dumb by A pissed-off New Yorker November 11, 2013

dumbhead 

A head that is dumb.

"You're a dumbhead!"
"Look who's talking, dumbhead!"

dumbhead by Shaka, Zulu Warrior May 22, 2006

dumbitch

1. A dumb bitch
2. A person that one hates for their overwhelming stupidity

Brian: "Man our teacher is so stupid!"
Mark: "Yeah I know, she's a dumbitch"

dumbitch by brin-paw December 3, 2005

dumb and dumber

A movie, but not just any movie, produced in 1996 by New Line Home Entertainment that is 113 minutes of pure enjoyment. The plot line is a magical duo and their cross country trip to return a breifcase to its rightful owner. This movie is full of cooky mishaps, moronic confusion, and just pure hillarious-ness. An unrated version has recently been re-released with never before seen footage. This is unarguably the greatest movie of all time and has had fans as slaves since the day of the release. Should certainly be reguarded with the highest of standards, for it set the bar for every comedy movie to follow. Simply Brilliant.

Hey, have you seen Dumb and Dumber!?

Yeah man, of course! I pissed my pants twice!

dumb and dumber by Excusemeflo x August 30, 2006

Dumbleburn

When Dumbledore or any other main harry potter character makes a sick joke at another character

To Mrs Dursley "knock knock, who's there?, not your sister, she's dead" (Sick Dumbleburn brah)

Dumbleburn by snowballsnowflakesnowmorenames March 5, 2015