"I notice that everyone in favor of abortion has already been born." - Ronald Reagan 1980, in response to a question on his position on abortion during the presidential debates.
"Keep Bush, Cheney, Ashcroft and Rumsfeld in office! After all, why change horsemen in mid-apocalypse?" - found on a website during the 2004 Bush re-election campaign.
In both sentences, humor is used sarcastically to make your speeches more acceptable and less thick or even absurd.