Freaking Sunday Drivers

I was on the Interstate a little while ago and the posted limit is 60 MPH. I was behind a Ford Expedition who was only going 50 MPH. I could see that the driver was just blabbing away with her passenger. I couldn't get around her because my exit was coming up and besides, everyone doing the speed limit was passing her. She then turns on her blinker to exit AND slows down although the exit is still half a mile away. How aggravating is that? VERY!!