Zac Efron's 21st Birthday Surprise

Zac Efron poses on the red carpet at ‘HSM 3’ premiere in London Zac Efron poses on the red carpet at ‘HSM 3’ premiere in London

“High School Musical” star Zac Efron turns 21 today – but girlfriend Vanessa Hudgens told Access Hollywood’s Billy Bush there’ll be no wild night on the town for the young actor.

“We are laid-back people,” Vanessa told Billy at the “High School Musical 3” premiere in LA earlier this week.

But, she said, they’ll be celebrating – and Zac doesn’t even know about it yet.

“It’s a surprise,” she said, laughing. “That’s the most you are gonna get out of me.”

One thing’s for sure — “HSM” co-star Ashley Tisdale seems to be a collaborator on the festivities.

“He doesn’t even know,” Ashley told Access. “It’s a complete surprise.”

“I can’t say anything,” she added. “Vanessa would be so mad.”

Though the ladies couldn’t reveal further details, Zac will no doubt get a not-so-secret belated birthday gift at the box office next weekend, when “High School Musical 3: Senior Year” hits theaters.

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