Back in 1948, during his first race for the US Senate, Lyndon Johnson was running about 10 points behind, with only nine days to go. He was desperate. And it was just before noon on a Monday, they say, when he called his equally depressed campaign manager and told him to call a press conference for just before lunch on a slow news day and accuse his high-riding opponent, a pig farmer, of having routine carnal knowledge of his sows, despite the pleas of his wife and children.
His campaign manager was shocked. "We can't say that, Lyndon," he supposedly said. "You know that it isn't true."
"Of course it's not!" Johnson barked. "But let's make the bastard deny it!"
Graphics and quote stolen from here.