It’s a very stupid internet joke.

It originated from an MMO video game where if you pressed F1 you’d empty your entire inventory, thus giving all of your items away to whomever was around to pick them up before you could.

This turned into deceit and trickery; people would tell new players that in order to do something they would need to press F1. Then when they did, they’d be tricked into emptying their inventory and giving all their items to the asshole who tricked them.

This evolved into a joke that people who were trying to pay respects on the internet should press the F key.

It’s dumb as shit, but the internet perpetuates mob mentality so it won’t go away until the next big stupid joke comes along that no one actually cares about.