What does FFFFF mean in runaway comics?

NETA of the FFFFFF group comes from the animation "Dumb Exam Summoner". There is an F class in which there are only two girls and a Xiuji, and the others are all men, so they are envious of the love in the class. All heterosexual people are to be interrogated as heretics, and they are all wearing headgear that says F during interrogation, so it is called FFFF Group.

Ps: Now all bachelors can call themselves members of the FFFFFF group (their main job is to burn couples) (just kidding).

See the attached drawing for details (please don't take it seriously)