Prince William can be playful, too.

In a documentary titled “Prince William at Thirty,” a colleague of the Duke and Duchess of Cambridge recalled a surprising incident involving the two. According to Helen McArdie, who occupied the room next to Kate Middleton’s in their hall of residents, she once caught the couple in a bar with the royal prince doing something cheeky.

“Ma Bells was a popular drinking location for them, also known as Yah Bells in St Andrews,” McArdie recalled.

“And I remember seeing the two of them at the bar and him pinching her bottom and that was the first time I remember thinking: ‘Well they’re definitely a couple then,’” she continued.

She also recalled humorous incidents involving the couple and their drinking habits. She shared how one time Middleton had to be carried back to her room because she was “paralytically drunk” and couldn’t walk on her own. She added that Middleton wasn’t the only one feeling that way as “we all were that week.”

On another occasion, Prince William reportedly fell into a bush outside their halls and had to be retrieved by his bodyguards. Despite these incidents, Prince William got to enjoy a private life as all of the students were warned beforehand to not speak about the future king to the press or they would be expelled from their halls and possibly the university.

The source went on and said that Prince William was treated very normally almost from the moment he arrived. She added that they were “starstruck” but tried their best not to show it.

During Prince William and Middleton’s engagement interview, the duke made a shocking revelation about their compatibility. According to the royal dad of three, their relationship works because Middleton has a “naughty sense of humor” which helps him with his “dirty sense of humor.”

Just recently, Prince William joined his wife at the Chelsea Flower Show where Middleton’s designed garden was unveiled. The couple was caught on camera welcoming Queen Elizabeth II at the event. The Duke and Duchess of Cambridge both kissed the monarch on the cheek. Middleton didn’t forget to curtsy to the Queen and she did it perfectly.

Prince William and Kate Middleton Prince William and Middleton meet with Irish Guards after attending the St Patrick's Day parade at Cavalry Barracks on March 17, 2019 in Hounslow, England. Photo: Getty Images/Gareth Fuller