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 payrespect"
"Press F (X) to pay respect"
On most computer applications, F1 is the keyboard shortcut to bring up the help menu. Thus, the phrase "Press F1" is most appropriately given as a reply to anybody who needs help, especially in the psychiatric sense.
<Joe> Oh my god, at lunch today, everybody stopped talking and I said, "Crap, the chat died." I really need to stop wasting time on IRC.
<Phil> Dude, you really need help. Seriously. Press F1.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).
Precedes or follows either a gratuitously disrespectful or honest remark, originated in New York City. Used in similar fashion to "no offense" or "to be honest," interchangeably.
Ya mans is wild buns, respectfully. Respectfully he's washed.
After school, The Modells on Jamaica Ave was active. Respectfully.