The premise: Homosexual fraternization is against the First Order code of conduct, but in practice it just means "don't do it on the ship." Occasionally, officers or Stormtroopers find out that when one has the ability to spend time at a port, it's easier to get laid by taking on a spontaneous side job as a prostitute. (And then to spend those credits on the same thing.)
Hux/Finn(/Poe), rentboy for fun