Theron plays a former high school 'mean girl' in director Jason Reitman's new comedy Young Adult, but the actress told ET Online that she spent most of her own high school years without any boyfriends or even many friends.
"I didn't have any boyfriends in high school," Theron said. "I had a massive, massive crush on this one guy. He was a couple of years older than me and I did not exist in his world."
She went on to say: "I was in a way like [the older version of her Young Adult character] Mavis, so disillusioned in it that I thought he was going to ask me to this dance.
"So much so that I told my mum I needed a dress and she went and got me a dress for the dance... and it never happened."
Theron previously admitted that she was bullied by more popular girls in high school.
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Young Adult opens on wide release in the US on December 16 and on February 10, 2012 in the UK.
Watch the Young Adult trailer below: