I met the Hatman before it was cool
One night when I was in middle school, I woke up at around 2 AM to see a silhouette wearing a wide brim hat looking down at me. I tried to cry out but I couldn't move a muscle, and by the time I could muster up a weak "...hey," he had disappeared.
That's right, the Hatman was literally my sleep paralysis demon.
Still thinking there was a strange man in our house, I tore through every room but my parents' bedroom looking for where he had gone, only to find that he had apparently left. (Side note: in retrospect I have no idea what I was trying to accomplish here. If a possibly violent intruder had broken into our house, an unarmed 12-year-old kid with no martial arts training was not going to stop him from doing anything, and the worst case scenarios of what he could have done to me if I found him are too bad to mention here.)
In the morning, I didn't speak a word of it to my parents, because I was still very freaked out and didn't want them to freak out, which would cause a vicious cycle of feeding each other's anxieties. If it had been a real intruder, this was a pretty bad plan, but later that day I realized what had happened was actually an episode of sleep paralysis.
I was a skeptical sort, and liked to read debunkings of alien abduction experiences and their ilk. Sleep paralysis was a pretty common explanation levied for many of these experiences. Not having had sleep paralysis, I confidently thought that I would be tough-minded enough to recognize whatever I saw as a hallucination right away. That night, reality kicked me in the face, and I realized that even the most skeptical and hard-headed types are just as vulnerable to our own brains' mismatches with reality.
I never did have sleep paralysis again, nor did I see the Hatman in any other context. Nor, for the record, did I ever use diphenhydramine (DPH) recreationally, but in high school I got pretty obsessed with reading DPH trip reports, and started to notice my old nemesis showing up. A long while later, after I had stopped reading TRs for fun, the meme inexplicably spread outside the DPH user community, and now I get to tell people that I met the Hatman before he was famous.