"Naff" is a word I infrequently use as a mild version of "shit". If something is a little bit bad or dull, it is "naff". I have just come across (via The Slate Gabfest podcast) one of the alleged roots of the word giving a ruder etymology: "not available for f***ing." This is backed up as a possible etymology here.
Is this word ruder than I though?
Its debateable whether 'sod off' is worse than 'piss off' though. The former was tolerated by teachers during my schooldays back in the 80s, while the former was not. Back then most of us were unaware that sod came from sodomy. This has probably changed though - I suppose the internet has made us much more aware/knowledgeable about both etymology and sex ;-)
– immutabl Nov 01 '11 at 09:22