ive heard two theories of the F word's origen
1. Fornication Under Consent of the King (F.#.*.K)
the initials were posted above the first legal brothels in england ... but i cant remember which king legallised prostitution as long as it was "controlled" in a brothel
2. the other is from the saxon part of our ANGLO-SAXON heriitage. originally it meant something similar...
I am not sure how you wouldd phrase the word in a satirical way... perhaps even the most sheltered 13yr olds have heard the word at least once, so by alluding to it in a similar way as in F@#$% etc. could be enough
