I've met so so many CKIA's in my time.
Here is my favorite today:
I worked part time in a department store (shoe department) while working full time in a post-degree mandatory internship at the local hospital in my field, CKIA had been working at the store for 3-4 years and was in school studying theater (I only mention this because I think I received a lot of his KIA lectures because I was the only other part timer not in high school/ younger then him and it bothered him that I already had my degree). Despite multiple conversations about my studies, he always firmly believed I was a nursing student (I wasn't). There's nothing wrong with that, but he would often end his 'truthy' lectures on high fashion with "It's ok honey, you're going to be a nurse someday" when I failed to keep up with his made up facts.
He was really notorious for knowing more then anyone about anything sold in the whole store (he had been there since it was built don't you know) badly enough that I mistakenly thought he was a manager my first few months there. Mostly I humored him and his crazily wrong stories about the history of our store and fashion - one really slow Sunday I got told the entire life story of Coco Channel - totally wrong, but amusing.
Then, one day (either Mardi Gras weekend, or St. Patrick's day) he came back from lunch panicked because two guys at the pizza bar across the plaza were trying to complete the 'world tour of beer' (150 varieties) in one day. I said "Don't worry about it too much, I don't think it's even possible to consume that high a fluid volume in one day, and I'm sure the bartenders will cut them off if necessary" and boy do I wish I remember exactly what came next because it's one of the funniest things I've ever heard.
He started sputtering and getting really worked up "Don't you know that beer is just poison and I KNOW that they ARE going to have 75 each and all that alcohol is going to go straight through the wall of their stomach and overload the liver, and the yeast from the beer is going to be bouncing around in the small intestine where the insulin shoots in and their blood sugars will spike right up and set their body into overdrive just as the alcohol gets into their brain where the nerve cells will eat it up and there will be too much insulin in the brain for it to function....."
I just stood silently by waiting for him to finish his crazy story (and double checking that there were no customers around) thinking that this was just one tirade of falsehood too many. When he finally finished I said, "Well, that is impossible" and briefly explained the physiology of how the body processes alcohol.
When I finished he sort of squinted/glared at me and said "You're in nursing school, aren't you!?" in the most condescending/accusatory tone possible, "well MY grandpa was a DOCTOR and he told me it happens just like I said it does and someday you will have to learn that Doctors just know more about these things"
ETA: At the time of this conversation it was just another day working with CKIA to me, and I was trying really hard to keep my cool and avoid it becoming one worked up KIA vs another worked up KIA, and I exited pretty quickly to get back to working, so I missed most of his reaction, but my coworkers assured me that the look on his face when I dared question his knowledge was priceless, and "well, that is impossible" became a department catch phrase for a short time afterward