First up, she had to do an impression of Cher singing "Frère Jacques", and she looked pretty terrified tbh.
But she obviously killed it, because she's Celine Dion.
Then she had to sing "Row, Row, Row Your Boat" to the tune of Rihanna's "Work".
She ~really~ got into the role.
But the best part by far was when she had to sing a lullaby in character as Sia.
She made sure to really get into character for this one, too.
You can watch the awesomeness for yourself in full here: