This must be number one on the list “phrases you don’t want to find yourself saying”. Or more accurately, be reported as saying*. It means one of only two things:

– your thoughtless play has inadvertently caused some ghastly and tragic accident.
– you are on totally the wrong side of a political argument.

In the former case the phrase adds a bit of cheap poignancy to a story of people being total idiots. Bits of fun here tend to include climbing pylons, larking about on railway lines, teasing lions etc.

In the latter case the phrase is a way to duck out of expressing contrition after you’ve been a knob. In its mild form it is found next to “We’re sorry for any offence caused”. In its more virulent form the mantra “blown up out of all proportion” is probably close at hand. The bit of fun – maybe a jolly racial epithet, or a bit of low level sexual harassment or maybe a sliver of gay-baiting – is often described as “harmless” and is generally being criticised by “busybodies”.

Phrases like that become common because they work. The offended party is thrown onto the defensive, smeared as humourless or socially inept. Unless your cause is particularly just you have to spend time explaining why something isn’t “fun” – that’s if you get right of reply at all. The liberal mind though tends to shy away from using “just a bit of fun” as a weapon, it seems reserved for the, uh, culturally traditional. The defenders of Jerry Springer: The Opera or Brass Eye have to use all sorts of cumbersome ideas like satire and free speech, for some reason they can’t just invoke fun and end it there. Wonder why?

*(Apologies to the member of FT staff who found himself in just this situation.)