I don't know who she is, but I'll be that she is not the stupidest person in the US.
(More seriously, you can't tell if a person is smart or dumb based on what he/she knows because different people are exposed to and pay attention to different things. For example, I have no idea who "Kramer", aside from a character on a TV show I have never seen, because watching TV fell off my priority list about 20 years ago, but just because almost everyone else around me does know, I don't consider myself dumb.)
-Ww