https://www.urbandictionary.com/define.php?term=Stan
I had to look it up; I was under the mistaken impression that Stan was the male equivalent of Karen, but I guess there are some similarities between them.
If there is one thing the incel or general far-right community has been very successful at, it's coopting and hiding behind popular vocabulary and arts - most notably Pepe the Frog, but also... have a look on how modern neo-Nazis look like at rallies. It used to be the case up until the 90s that neo-Nazis could easily be spotted: shaven head, Lonsdale/Consdaple clothing, combat boots. Nowadays, they show up in everyday ordinary clothing, listening even to rap music, wearing all kinds of hairstyles.
For instance you could almost figure out what ‘anti-racism’ is based on the composition rules of language. (But you might think “anti-“ means “opposed to” whereas “anti-“ as in anti-matter is more like it according to Coates.)
Someone who went to the movies might dimly understand the “pills” (or do some people just take a lot of drugs?). On the other hand you could never figure out “chad”, and “stacey” without explanation.
Shaka, when the walls fell.
Or, you know, context.
I don’t know what a Stan is but could easily understand what they were referring to by the way they used the word.
Incels? What’s that? Pots that call the kettles black?