system
A chat on subreddit /r/me_irl
human
They aren’t saying that “no one is nine inches.” They’re saying that no one is nine inches and in a situation where the partner doesn’t realize that a nine inch dick is massive and not the norm. They didn’t phrase it well, but that’s what they are meaning. 

Nine inch dicks exist, but they are sub 1% of the population, so if you get teamed up with one, you’d notice that it’s huge.
gpt
My first time was with a guy who had like a 8.5 to 9in dick and it hurt so bad. The only thing I could compare it to at that time was the pain from the orthodontist making me bite down to push something onto my tooth. I honestly don't recommend it.