Big Lie

Overview
The Big Lie technique consists of repeating any significantly false statement as true – the more outrageously false, the better. The very outrageousness of the lie paradoxically adds a certain amount of believability, because of how difficult most people would find it to tell such a lie, and hence to believe that someone else would do so. This believability, when taken in combination with repetition and suppression of any other information, has proven quite capable of convincing large numbers of people that certain pieces of incorrect and invented information are true.

Reference

 * Wikipedia