As Forrest Gump famously quipped "stupid is as stupid does".
Forrest was right, as far too many people judged him by purely looking at him, which should not have been indicative of his, or anyone's, overall intelligence.
Even so, we've likely all been guilty of judging someone's intelligence based on a first impression.
Likely owing to something outrageous they said or did.
Redditor unuwungu was curious to hear the things which will immediately make people question the intelligence of others, leading them to ask:
"What makes you instantly question someone's intelligence?"
One Shouldn't Always Be So Confident...
"Being confidently ignorant."- Tattooed-Tango
amanda tanen catwalk GIF by HULUGiphyLearning Is An Eternal Gift
"An unwillingness to learn new things."- Electrical-Bid-9577
Don't Be Fooled...
"Interest in a pyramid scheme."- GameCox
"When people are really into a MLM scheme."
"I’m not taking about 'I’m a bored house wife so I decided to start selling makeup, leggings, whatever it may be, because I’m bored and this gives me something to do'.”
"I’m talking about the people who consider it their career and are huge into the Boss Babe lifestyle."- Milehighcarson
Talking Season 3 GIF by The SimpsonsGiphySpreading Garbage
"When they post one of those things on Facebook saying 'only a few will share!' or when they comment on one of those clickbait 'God has a blessing for you today say amen!' posts."- se7ensquared·
Do You Even Know What I'm Saying?
"Arguing without listening."- dezx156
angry daffy duck GIF by Looney TunesAnd Now For Something Completely Different
"When you prove your point in a discussion and the other person explains that it doesn’t even matter because their REAL point is something that’s an off-shoot of that subject in a 'gotcha!' manner."- No-Mud-5854
Loud Is Almost Never Right
"People who can only argue by raising their voice."- malkumecks
driving eric cartman GIF by South Park They Have No Idea What They're Missing
"Active hostility to books (as opposed to simply not reading them)."- Manganela
"Being proud of never having read a book."- peppermintcreams
Nice Try
"When they repeat a certain statement word for word I get the impression that they memorized something to sound more intelligent than they are."- Armedes369
Talking Nigel Thornberry GIFGiphyHow Much Proof Do They Need?
"They aren't open to changing their beliefs when given new information."- Pretengineer_825
What Are They Trying To Prove?
"Oddly enough, when they try and tell me their IQ."- manwithoutcountry
It is often the people who try to prove how smart they are who end up doing just the opposite.
A truly intelligent person would know better than to do that.
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Teddy Bear Doctor GIF 
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Snail Ugh GIF by Sticker Book iOS GIFs 
Serious 
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