A phrase used in a mocking sense on 4chan, often as a reply to people to discredit their opinions due to them being transgender.
Due the anonymity on the site, every post looks the same, meaning people can imitate each other at will. So someone who might want to make fun of another person would say this as a reply, imitating an edit or additional note by the original poster.
"I think that the Elden Ring game is good."
"I'm trans btw, not sure if that matters." (<-- not the original poster)
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)