It can happen to anyone...you're in the middle of your live shot and you totally forget what you're trying to say.
But, it's extremely rare when it happens at the network level.
On Saturday night's CBS Evening News, Correspondent Terrell Brown was tagging out his story from Boston Live.
Brown tripped over one word and then absolutely lost his train of thought. He made no sense in his stumbling and then pulled the rip cord and sent to back to the studio.
Here's the very awkward video: