Billie Eilish rang in her 21st birthday party with a star-studded party at The ... which reads "been a good girl for 21 years" on ... Shop Billie Eilish's Limited Edition 21st Birthday T-Shirt.

For her 21st birthday, Billie Eilish donned a sexy Santa suit. Instagram/billieeilish. ... December 18, and celebrated in a custom T-shirt that read “Been a good girl for 21 years. ...

Paris Hilton wore an updated version of the iconic silver chainmail dress from her 21st birthday party to perform "Stars Are Blind" with Miley Cyrus on New Year's Eve.