Hilary Duff and Joel Madden dated from 2004 to 2006. Credit: Jesse Grant/WireImage

She’s been the girl next door since age 14, but Hilary Duff doesn’t have a problem shedding her good girl image from time to time. In the April issue of Cosmopolitan, the Younger star, now 27, opened up about the public’s perception, and her reality. 

“I don’t have to prove to people that I’m an adult now. I am an adult,” said Duff, who indeed is mom to son Luca, 2, with future ex-husband Mike Comrie. “It’s frustrating to be put in a box, but I never needed to wild out to show that I’m grown-up.”

One naughty allowance she did make: a top secret friend with benefits! 

“I’ve enjoyed myself,” she said when the Cosmo reporter asked if she previously had an “eff buddy.” “I think everyone should have something where you know it’s not exactly what you’re looking for but you just have a wicked good time. That was freeing for me and a bit of an awakening. It’s fun to have a secret.”

Many fans have been fixated on when (and with whom) the newly single mom first lost her virginity. 

“I had a 26-year-old boyfriend,” Duff said of Good Charlotte rocker Joel Madden, whom she dated from ages 16 to 19. “So everyone can make their own assumptions about what I was doing.”

Madden, 36, is currently married to Nicole Richie, whom he began dating a month after splitting from Duff in 2006, and the couple shares daughter Harlow, 7, and son Sparrow, 5. 

One way the former child star has been able to keep it classy is thanks to eliminating the negative people in her life. 

“At 19, I did a massive friend cleanse,” she revealed. “That was really hard, to sit down with people and say ‘We can’t be friends anymore.’ They were like ‘That’s f—ked up; you’re a bitch.’ But having a good reputation was important to me. That’s not to say I didn’t screw up and do little naughties here and there.”