David Letterman made a joke the other night about Sarah Palin's daughter going to a Yankees game and being impregnated by Alex Rodriguez (video below). Now, humor of the joke aside, can you imagine if a conservative host had made a joke about one of President Obama's daughters? What do you think the media's reaction would be? I think the joke is more about Rodriguez and his alleged antics with other women, but it also incorporates Palin's daughter in a rather unfortunate way.