Gossip needs a relay team. Drop the baton.

A rumour travels exactly as far as the next person willing to carry it. Nobody in the chain feels responsible, since each one is only repeating what they heard, and the story gains speed and detail with every pass. Stopping it costs you the small pleasure of having something to tell, and nothing else.

When something arrives about a person who is not in the room, decide not to pass it on and change the subject without making a speech about it. If you know the person, ask them directly instead. Chains break easily and quietly at any point along the line.