[thrownawaysz]

Interestingly there are some not so good sources

>F

>[SE fail, also used as a mark for inadequate work, or fuck!]

>(juv.) response to someone else’s bad news.

F doesn't come from fail but from Call of Duty

https://en.wikipedia.org/wiki/Press_F_to_pay_respects

https://knowyourmeme.com/memes/press-f-to-pay-respects