The sister trio appeared on Thursday's episode of the iconic children's show to sing a new tune explaining the ABCs alongside Elmo, Big Bird, Cookie Monster, Burt, Ernie, Oscar the Grouch ...

For the most part, Elmo looks the same ... For years on the show, Snuffleupagus was Big Bird's imaginary friend and many other muppets on the show questioned his existence. Later, in the 1980s ...