Controversial statement to generate discussion is called..?

[adredwood]

I'm looking for the name of something a friend told me about last year, and I've completely forgotten the name of. It's a warmer sentence you can put on the board, a statement designed to generate discussion and it has a name... I just can't remember it.

Examples might be:

Poor people are happier than the rich
The city is more interesting than the countryside
Video games can never be art

I know there are websites devoted to this sort of thing, I just can't find them, despite searching for 'esl lesson warmer controversial statement'. Any ideas folks?

Andy (: