I'm intrigued

Maybe man's Estonian. Caviar in Estonian is "kalamari" which means fishberry

What is this, a Seinfeld episode?
Jerry: "How'd the date go last night?"
Elaine: "Ugh, total bust! We spent the whole time arguing about calamari!"
Jerry: "Arguing about calamari? Like fried squid?"
Elaine gestures there you go
George: "It's deep fried, what's not to like?"
Elaine: "He doesn't even know what it is!"
Jerry: "Never had calamari? What a sad life..."
Kramer enters. Applause.
Elaine: "Kramer. What's calamari?"
Kramer: "Disgusting. That's what it is."
Jerry: "We're not talking about the same calamari here."
Kramer: "It's like chewing on rubber bands!"
Jerry: "You're not still going to Bosco's are you?"
Kramer: "I like Bosco."
George: "Didn't the health board shut them down?"
Kramer: "That's how you know it's authentic."
Elaine: "Can we get back to my problem, please?"
Jerry: "I'll tell you what, let's all go out. Elaine, you can bring you can bring your boyfriend. I'll show you all what calamari is supposed to taste like."
Elaine: "Well, do the have caviar?"
Jerry: "Caviar? What am I made of money? Why caviar?"
Elaine: "That's what he thinks calamari is!"
George: "Did you correct him?"
Elaine: "Yes, George, I corrected him. I corrected him for 45 minutes!"
Kramer: "Well why didn't you just order the calamari and show him?"
Elaine: "We were at a coffee shop."
Kramer: "Oh, they don't serve calamari at coffee shops."
Elaine: "...I know. I didn't expect to have to defend the reality of what calamari is when we made the date."
- Were you a writer for the show, what the fuck, this is so accurate
  
  It's shockingly easy. There was a whole reddit subreddit dedicated to inventing new Seinfeld scripts
  
  I've only ever seen a couple of episodes and I was shocked at how well this script fit what I've seen.
- Damn. Bravo!

Nice of him to get the red flags out on the table early though!
- Calamari is a red flag? People can be wrong...
  His one visible mistake is not backing down when confronted with a different opinion and re-evaluating.
  
  His one visible mistake is not backing down when confronted with a different opinion and re-evaluating.
  Refusing to back down is the red flag, yes
  
  Facts and opinions are two different things.
  
  Somehow you're the dumb asshole on two of the last two threads I read (the other one being about appropriate songs on a hiking trail). Impressive.

Reminds me of that 4chan post where anon gets stopped by a stranger who tries to explain that Aluminum is the best metal. Anon tries to stay calm and explain the iron is the best metal, but the guy just kept going off about Aluminum and started talking about rust and ruined Anon's whole day.
- The concept of "best metal" without specifying for which purpose is pretty ridiculous, so to me the anon in your story is equally guilty of causing his own bad day.
  
  Well, no.
  The best metal is obviously bismuth:
  
  Especially because the answer is obviously Tin
- Aluminum is a weird choice because it’s almost always alloyed with other metals.
- stranger is correct, aluminum is extremely strong and flexible

Seen something like this before. Guy was testing his date to see if she would correct him and she would fail if she did.
- I remember reading Ron DeSantis (governor of Florida) said he did this on dates. He would say Thigh Food for Thai food. If they corrected him he wouldn't date them again.
  He's married now and I wonder if his wife ever offers to pick up Thigh food for dinner.
  
  I do love some thigh food. The nectar of the gods.
  I also love how he does the red flag ass version of this. He must be right. Not like playing mental games is ever great, but nothing more nail on the head than a Republican looking for subservience and weak will.

An ex and I were on a bus trip to a city about an hour away from where we lived while we taught English in Korea. The subject of there being a "subway" in said city came up randomly. She said she thought she had seen one the last time she was there. I had been there more times than she had and said there was no subway. She doubled down. No, she was quite sure she had seen one near the university. I doubled down, I've been there quite a few times. There's no way they have a subway. It's not even big enough for one! It got pretty heated. This went on for some time. Feelings were hurt.
She was talking about the sandwich restaurant, and I was talking about underground trains. We were both right.

If you need to Well, actually… on your first date, all your dates will be firsts!
- Well actually, any subsequent dates wouldn't be my first ever date /s
  
  Keep this up and we'll upgrade you to having 0 dates.

Now we need to know what OP thinks calamari and caviar are. It could be a 6' situation where guys invite girls to caviar but order calamari. First hint is that she uses singular for calamari.

I've been the side guy in a similar date in a bar. But instead of calamari is fish eggs. The dudes deeply held belief was the flat earth lie.