Zac Efron hasn't always been so immaculately-styled, especially when it came to his own senior year prom.

The High School Musical star reveals that he hit the thrift stores on the hunt for the perfect prom night vintage tux.

"I had the brilliant idea of wearing a vintage tuxedo. I was determined to find one so I went to Goodwill," Zac tells Entertainmentwise.

But his fashion find didn't go to plan.

"It never really worked out - it looked really bad and it wasn't quite as glamourous as my senior prom outfit for High School Musical 3," he added.

Zac's co-star Ashley Tisdale also let us in on a few of her wardrobe secrets in High School Musical 3: Senior Year.

The actress - who plays Sharpay - is know for her character's trashy outifts and decided to up the bling factor for the third instalment of Disney phenomenon.

“In the 3rd movie I had a lot of say in my clothes – she still wears pink but she is a lot more mature,” she says.

“We decided to rhinestone all of Sharpay’s things – including her cellphone."

See the High School Musical kids out in London where they are promoting HSM3: Senior Year