F in the chat means to pay your respects. They are mostly on streams like twitch. The term originated after a feature in the 2014 release of Call of Duty asked players to press F on their keyboard or X on their controller to “pay respects” to virtual fallen soldiers.
similar to RIP! used in circumstances to show disapointment
ex. "I just failed my test!"
"my mom just died"
"I can't find my juul"
"My cat got hit by a car"
and to all you can humorously say, "CAN I GET AN F IN THE CHAT" and it works oh so perfectly.
older people might not understand but it is truly wonderful
mom: (to my dad) honey, i found your texts with kathleen! who the hell is that???
me: can i get an f in the chat for dad