You know what? I think that the adverts are specific to the threads in some way.

There's a thread directed towards the3rddoctor and the advert at the top of the screen was selling Dalek figures!

I'm guessing that if I write the word "pizza", that pizza adverts will start to appear!

pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza, pizza.