Kate Middleton
Kate Middleton arrives to launch a new national support line at the charity Family Action on Jan. 22, 2019 in Lewisham, England.  Getty Images/Adrian Dennis

Kate Middleton had naughty moments when she was still in Marlborough College.

The Duchess of Cambridge is a picture of grace and elegance. She is always poised and classic. However, she also had her fair share of mischievous streaks when she was younger.

According to the 2011 documentary “Kate Middleton: Biography,” she had very little confidence when she first arrived at Marlborough. However, she decided to emerge from her cocoon when she was 16.

Middleton’s antics reportedly included flashing her bottom for the boys staring from the window. One of the duchess’ schoolmates, Jessica Hay, claimed that Middleton “kind of got addicted to it” that over the course of one year she did it no fewer than 90 times earning her the shocking moniker “Kate Middlebum.”

The Duchess of Cambridge’s naughty side is not a secret to Prince William. In fact, it’s one of the things that the Duke of Cambridge considered as something that made them compatible.

“She's got a really naughty sense of humour which really helps me because I've got a really dirty sense of humour so it was good fun, we had a really good laugh, and then things happened,” Prince William told Tom Bradby.

Aside from that, Middleton was reportedly involved in a number of relationships during her stay in Marlborough. The duchess’s first kiss was with the older brother of Alice St. John Webster, one of her closest friends at the school.

Middleton was reportedly heartbroken when their relationship ended. However, she remains friends with Webster. She even invited and gave her a prime seat at her royal wedding to Prince William in 2011.

Middleton was also romantically involved with Harry Blakelock, captain of the Marlborough College rugby team. However, their romance was short-lived as Blakelock left school for a gap year.

Although Middleton dated a number of boys, she didn’t actually have a string of boyfriends as she was reportedly “saving herself” for someone special.

In related news, Middleton is set to be a queen consort when Prince William becomes the new king. According to royal commentator Victoria Murphy, the Duchess of Cambridge “earned her position” as she made a lot of things look very easy even if those things were not natural for her.