One guy will speculate, or actually put an opinion out as fact because he believes it, and states it very emphatically.

The next show up then plays on it, and the host or hosts say "I'm hearing that......" or "People are saying that........" and it goers from there. After a few different people have repeated it there is a sense of truth to it because "an awful lot of people are saying/reporting.........." and away it goes.

There is a "technical" name for it that escapes me right now but it's also commonly used by politicians (as you may have recently heard lol).