Where did "F in the chat" come from?
I know what it means, but I have no idea how the letter F came to be associated with sad stuff.
Typing an F in the chat of a video game stream is a way to (often jokingly) pay tribute to a dead character or some other unfortunate thing that's befallen the player. It originated in 2014's Call of Duty: Advanced Warfare, where, in a scene at a friend's funeral, players on the PC are prompted to hit the F key to pay their respects. Lots of people thought the forced action during a memorial service was a bit cringy, so "press F to pay respects" started getting used sarcastically, and it spread from there.
People put F so they could follow up without leaving a comment instead of putting on notifications