At the start of Operation Good Hope, US forces were supposed to land on the beaches of Mogadishu under the cover of darkness. Instead, they were met by CNN who was covering the landing live on television.
In 2015, a journalist wanted to prove that the media will be quick to grab on any scientific claims to make news. He fabricated a study that claims chocolate helps in weight loss, got it published, then released it. He succeeded, fooling 20 countries.