Plot: TAYLOR SWIFT is back! The country music superstar is always so sweet and so much fun when she swings by to visit Ellen -- and today she'll give the world premiere performance of her song "The Story of Us. " No one will be able to take their eyes off the screen when sexy JON HAMM stops by! He's not just good looking, he's got a great sense of humor, and he's putting it to use in the new comedy, "Bridesmaids