Vanessa Hudgens found it ''horrible'' eating out of bins for 'Gimme Shelter'.

The 'High School Musical' star immersed herself in her latest role as homeless pregnant teenager Agnes 'Apple' Bailey, but found a scene where she was scavenging through rubbish quite traumatic.

She told RedEyeChicago.com: ''Eating out of the garbage was horrible because there was a paparazzi there that day so pictures are out of 'Vanessa eating out of the trash,' and I'm like, 'No, it's Apple'.''

However, Vanessa made sure the item she was scavenging for - a peanut butter and jelly sandwich - was edible when she got to it.

She added: ''It was great! I made sure it was going to be safe and clean, but it was still uncomfortable. It's a very real moment I think too for the character because that's something that really does happen when you're homeless. It's such a low point for anyone. It just doesn't feel good.''

The 25-year-old actress also said she had a ''panic attack'' filming another scene where she steals a car.

She added: ''The stealing the car was really traumatic for me for some reason because the guy who tells me to get in the car, his name was Jeff, was kind of my bodyguard, he was looking out for me the whole time.

''They wanted me to drive the car really close to him and he bangs on it and yells at me, and it was so much to take all at the same time that I just had a panic attack and I kind of lost it for a second because it was really overwhelming.''

Vanessa gained 15lbs for the movie - based on a real girl's experience - as well as cutting off her hair on camera during filming, and enjoyed the challenge of transforming herself.

She said: ''The grimier and uglier I got, the more I was like, 'F**k yeah.' ''

The star even got so into her role, she burst blood vessels trying to portray giving birth convincingly.

She admitted: ''I popped a bunch of blood vessels in my neck and face from pushing so hard.''