The word 'Naff' used in the 1970's BBC comedy Porridge as a replacement for the word Fuck. 'Naff off' the guards in the prison would be told, but naff is a Polari word. Polari being a language used by gay subculture in Britain mainly between the 1950's and 1960's. And before 1967 when homosexuality was decriminalised in Britain, naff meant in polari, Not Avalible For Fucking, used to indicate a straight or heterosexual individual.
The antonym of naff is tbh (pronounced t b h) which means To Be Had.
Another interesting fact about word usage in the 1960's is that when homosexuality was decriminalised 'Fag' and 'Dyke' was largely replaced with 'Gay', originally meaning 'promoting a feeling of cheer'. This is interesting because up until the decriminalisation, homosexuals where seen to be very sad and lonely individuals.