A rhetorical exclamation used to imply the idiocy of a person, behaviour or circumstance.
“Nobody tryna pay full fare on the TTC, are you dumb?”
by TorontoDictionary September 22, 2018
When some asshole says something so stupid you want to say "why man", you just ask them if they're dumb.

If they say no, then they're dumber than you even thought.
Idiot: Justin Bieber's the greatest singer ever!

Normal Human Being: Boi, are you dumb?! My CAT sings better than that bitch. Get a life, man.
by It'sCakeAtStake March 19, 2019
A rhetorical exclamation used to question an individual's intelligence. Both options in the question are purposely kept the same to reinforce the individual's low intelligence.
Widely known as the signature catchphrase of Daniel "Dexti" Su in the esports landscape.
Ali-A: Earth is flat
Dexti: Are you dumb or are you dumb?
by SuperCraft144 July 19, 2020
Daniel Su: says anything
Ali: Are you dumb or are you dumb
by JuicyDad69 December 10, 2019
The reply given to someone who says something which you believe to be false, untrue or against your opinion.
R.H: "Arsenal are going to win the Premier League this Season"
S.K: "Are You Dumb!!!!!! Its gonna be Man Utd!
by Skeen Age June 16, 2008
A term used often in place of a lengthy insult regarding someones intelligence, commonly this term is used when the party it is directed at is believed to only have the ability to comprehend two words at one time.
Jimmy says "I went out back yesterday and stole my dogs fun stick"
Bob retorts "Jimbo... You dumb."
by aidstroll May 10, 2007
A term usually used when someone says something they think is funny but it is actually fucking gay. Best used during the akward silence after the fuck face is done speaking.
"That picture is really cool."
"Thats what she said!"
....................... "YOU DUMB!"
by king josh April 9, 2008