This great talent puts on an amazing and mesmerizing show with many of his characters as a „song and dance man“. He was portrayed by Jim Carrey in the movie Man on the Moon (must see) and also had a very memorable appearance at Letterman in 1982. Also make sure to listen to his performance of „friendly friendly world“:
Andrew Geoffrey Kaufman (January 17, 1949 – May 16, 1984) was an American entertainer, actor, writer, performance artist and comedian.
Definition from Wikipedia – Andy Kaufman