There's no such thing as a stupid question --- wait, yes there is.
That’s Not How You Use Bear Spray

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I worked at REI a few years back (large outdoor sporting goods co-op, just in case you haven’t heard of it), and we sold bear spray (pepper spray for bears). A woman came in with her two kids one day and bought a canister because they were going camping. She gets to the front door, then comes back to the register as an afterthought, and asks if she’s supposed to just spray her kids from head to toe with it.
The Doors Lock Themselves, Don’t They?

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Gas station. “Hey, the bathroom door is locked. Can I get a key?” “There’s no key, if it’s locked there’s someone in there” “How does it know?” “How does… what… know… what?” “How does the bathroom know someone is in there?”
“People…. people go in and then they lock the door while they’re using it.” [5 second pause] “Ohhhh” This was a 20-25 year old guy who wasn’t obviously intoxicated.
Take Away the Credit Card

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“Yes, I understand I haven’t paid my credit card bill in 3 months. But why can’t I use my card?” “Because you haven’t paid your bill in 3 months.” repeat
We All Have Priorities

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“What do you mean I can’t bring my 6 month old baby into the nightclub?”
Children of the Sweet Corn

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Customer: Where’s the sugar?
Me: What?
Customer: I ordered sweet corn, this is just corn.
Something’s Missing

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Customer screaming: “MY NEW CAR’S BACK WIPER DOESN’T WORK!!!”
we walk outside, look at back window
Me: you don’t have a back wiper blade.
Funny Solution to a Cheeseburger Problem

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Fast food restaurant 1. Customer: “How fresh is your soda?”
Me: “Um it comes out of a box…”
Customer: “I Guess I’ll get water”
2. Customer: “Can I get a cheeseburger, no Cheese”
Me: “So a regular hamburger”
Customer: “No a CHEESEBURGER NO CHEESE”
Gave them a Regular hamburger in a cheeseburger wrapper
No Cutting, Please

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I’m a cashier at a grocery store and one time I had a lady ask me of I could “tell everyone else to let her go first.” Like, she expected me to force everyone who had been patiently waiting in line to let her cut them. It wasn’t like she only had 1 or 2 items either; her cart was packed.
At Least He Didn’t Blow Into the Straw…

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“Can you aerate that for me?” He wanted me to stir his apple juice. Technically his word choice was applicable, I guess, but wtf, dude? He had a straw ready in his hand and he could damn well have aerated that juice himself. I admit it took me 2 seconds of staring at his serious face before I reached for a straw, unwrapped it, and stirred his drink. I did it all without breaking eye contact with him, and he was satisfied. Also I think about him now every time I stir or shake my chocolate milk to make it frothy.
It’s Closing Time

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Not really a question but once when I was a deli clerk a guy came in at 9:59pm we closed at 9:30 so we had time to do dishes,mop, clean slicers,etc. We were supposed to be clocked out by 10 and i was still mopping the floor so I was already a bit behind schedule. A guy comes up to the counter and is like “UM EXCUSE ME WHERE’S ALL YOUR FOOD?!?” I said “I’m sorry sir we close at 9:30” “WHAT?!?” he exclaims “YOU GUYS SHOULD STAY OPEN LATER SOME PEOPLE HAVE TO WORK LATE AND NEED TO EAT YOU KNOW” I stared at him for a moment before smiling and saying. “Yeah I’m sorry sir I know the feeling.” He looked at me very confused before I’m assuming it registered to him that I’m still working, and walking off in a huff. This was also a bit confusing to me because he’s in a grocery store, he’s literally surrounded by food. Including cold tenders he can heat up in a microwave.
Just Because I Have a Computer…

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-Can you photoshop some pictures for me?
-Sir, this is a bookstore.
-Yeah, but I see you have a computer right here.
Large and in Charge

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I very briefly worked at a Wendy’s some years back and I was working the drive through. A woman ordered two meals, one with a small drink and one with a large. As I handed her the drinks she asked, “which one is the large?”
The Art of the Deal

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More of a story for context, but still hilariously dumb. I was working at a car battery store, when a customer came in with a receipt for a battery he had bought a couple weeks ago, asking for a refund. I asked him if he had the battery with him, so that we could take the battery back and refund him the money, when he said, “No I don’t have it anymore, I put it in a car I just sold.” Confused, I replied, “You want us to refund you for a battery that you don’t have anymore?” He responds, just as confused, “Yeah well I don’t have the battery anymore, so why should I have to pay for it? You need to refund me.” He did not leave the store happy that day.
Too Stupid to Use a Computer?

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This was few years back, customer (very chill guy) called in saying he recently bought a new MacBook Pro and it’s not working. I asked him ” What happens, when you press the power button” he said ” I don’t know where that is”.
You Mean Eyeglasses Don’t Work Like That?

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Once, while working at an eye doctors office, a woman was upset because we were charging her to make new lenses with an updated prescription asked “why do you have to make new lenses, just inject some more medicine in the ones I already got?”