I've never got it and I've been googling programming stuff for almost a decade now.

However, maybe I'm remembering wrong, but a few years ago I was reading an article about it and someone showed a search term that brought it up for them and I tried that term and got it. Dont remember what the search term was, but I think it was something related to one of the popular leetcode-esque algorithms I've never had to do in my hobbyist or professional work.

I've never seen it, but other people in my (non-US) country claim to have seen it. I always assumed it was either my taste in porn or the fact that I'm usually logged out and regularly clear tracking cookies.