The teddy bears have been using secret messages amongst themselves so others don't know what they are saying. They started by using the lolly stick method which they talked about in one of their previous stories (you can read that again by clicking here).
That particular method involved several items to be found before it could be used - they needed wooden lolly sticks and a marker pen. Scary had told them then that there were other ways of passing on secret messages and they wondered if there was any other method where they didn't have to find things to use first.
So they asked Scary if he had any other ideas. "Oh, loads!" he said. "How about I show you a way that doesn't involve any sticks or pens?" The other bears were all ears. "All you need are your voices!" he continued. "Although I will explain afterwards some other ways of using this method which might need you to find other stuff first."