As opposed to his heartthrob image, Zac Efron's girlfriend might be stunned to see him out of his element in 'Running Wild with Bear Grylls.' In an episode for the venturesome series, the 'High School Musical' actor had to complete a series of daring tasks including munching on worms.

"A reliable source of food is always under the ground, in the earth - good old worms," advised the survival expert to Efron. During the two-day challenge which prompted him to jump out of a helicopter, rappel down a staggering waterfall, and crawl across a thin rope over a mountain, Efron was unable to find food. To survive, he had no choice but to rely on worms.

"Just remember you've got to chew it - you don't want it wriggling all the way. Otherwise it might crawl out of like a weird orifice or something," said the British adventurer.

While Zac Efron's girlfriend should give him credits for managing to eat worms, the 'Neighbors' star admitted that it made him feel guilty: "Watching worms boil in egg is just disgusting, there's no way around it. They're just writhing in worm pain. It's kinda sad - but to survive sometimes takes a couple of worms."

At some point in the episode, Grylls got the opportunity to tell Efron about his fear: "I can't dance. I'm not joking. The fear of God would come over me."

He also talked about Zac Efron's 'Running Wild with Bear Grylls' appearance: "He's used to the screaming of millions of fans - but this time it's Zac that's gonna be doing the screaming."

In the episode of the NBC series, the 'Safe Haven' actor also opened up about his rehab stint and how pressures from Hollywood affected him: "You spend a lot of time in your house, going crazy and pretty soon you need a social lubricant."