In my experience, it is impossible to get the majority of people to stop posting to inane threads. What i have found works better is posting to the thread, but only posting flippant comments and jokes. That way the thread doesn't usually turn into a row, we all have a laugh and the starter of the thread doesn't get a rise out of anyone, so gets bored.

Just a suggestion, feel free to ignore my jabberings.

Bagpuss