Am also tempted to suggest (in homage to MrsBadger's former teacher) 'meta-thread' for what happens when the thread stops discussing the topic raised by the OP and starts discussing itself instead.
Like I'm doing now, in fact...
(MrsB - Had a similar thing with a South African who told me she wouldn't be able to stand living in the UK because of the 'wit'. Took me ages before I realised she was talking about the weather, not the sense of humour. In my defence, I should say that I was young and very wet behind the ears at the time!)