Vanessa Hudgens got a big surprise Monday night – a group of about 100 friends gathered at East Restaurant & Lounge in Hollywood to celebrate her 21th birthday.

Hudgens, decked out in a black mini dress with lace cut-out arms, arrived with beau Zac Efron in a chauffeured Audi Q7, and "when she walked in was completely surprised!" says a guest at the party.