updated 07/22/2012 AT 9:00 PM ET
•originally published 07/22/2012 AT 9:15 PM ET
The pop star, who turned 20 Sunday, was serenaded by the crowd of thousands (which included some of the most talented teen-friendly singers, including Taylor Swift) gathered at Los Angeles’s Gibson Amphitheatre as she was presented with yet another birthday treat: sparkler-topped Sprinkles cupcakes. Of course the b-day sweetie shared with the audience!
“This is the best birthday present ever,” she said after she was presented with her Teen Choice surf board.