Press F to pay respect 

It is a (semi-funny) response, seen a lot on social media like reddit, for example for someone with no chance of surviving a gaming battle due to enemy superior force , originally from 2014 first-person shooter Call of Duty: Advanced Warfare. Quoting know your meme :

"Press F (X) to Pay Respects is an action prompt featured in a quick time event from the 2014 first-person shooter Call of Duty: Advanced Warfare. Upon the release of the game in November 2014, many players of the game mocked the funeral cutscene for its forced element of interactivity that seemed out-of-place at a memorial service."

F
"Press F to pay respect"
"Press F (X) to pay respect"

Press F to pay respect by MoFazul September 21, 2017

press f to pay respect 

When someone has taken a BIG L or has been oofed so hard that they may feel emotional pain

This term can be abbreviated to the letter F

Man : "i got regected last week"
Everyone : "F"

Press F to pay respect is a general term or responce after someone feeling emotional or physical pain

press f to pay respect by Yognaught_001 July 25, 2019

press f to pay respect 

An action in a funeral in CoD: AW when ur best friend died

Some random cmt on youtube: this guy died yesterday, press f to pay respect.

press f to pay respect by Daufq da Gamer May 7, 2017

Press F to Pay Respects

When someone you love passes on, so you pay your respects with F

Damn, my cousin died.

Press F to pay respects, am i right?

Press F to Pay Respects by ShaneThy Nugget September 26, 2018