Princess Diana was known for her compassion, style, and groundbreaking charity work, but those close to her have revealed another side of the royal family that the public did not always see: her mischievous sense of humor.

On September 26, Richard Dalton, Princess Diana's former hairdresser, shared an anecdote from his days styling her on Fox News.

According to Dalton, who first met Princess Diana when she was 17, the Princess was particularly fond of practical jokes. One of her favorite gags was to sneak gag items into the briefcase of an unsuspecting victim.

“She always had a stash of fake vomit, which she would put in her private secretary's briefcase, or dog poop in the hallway ......”

Dalton, who described Diana as having a “great sense of humor,” said the “kind and charming” Princess Diana hired him to do her hair full-time after previously working with Diana's sister.

He recently collaborated with Princess Diana Museum founder René Plant on a book about his experience, and the two discussed their project, It's All About the Hair-My Decade With Diana, on Fox News.

Plant said the book has “little moments throughout that have never been told before” and that she “really liked all the funny parts of the book because [Diana] was really wicked funny.”

“She would tell crude jokes,” a Diana expert told Fox News.

Dalton also revealed another hilarious moment involving her famous teased hair, sharing that then-Prince Charles “banned all aerosol hairspray” because of his passion for environmental issues.

The hairstylist said, “When we got to the palace, I said to the princess, ‘You know there's a hole in the ozone,’ and she said, ‘Really, what does it look like?’

He told Fox News that the two “laughed about it,” and Plant noted that despite Charles' protests, they “continued to use” L'Oreal's iconic Elnett spray.

Dalton told the outlet another sweet detail that Prince William loved getting his hair cut and that he was trying to get extra cuts even when he didn't need them because it meant he would get “extra TV” time.

After all, Plant said, Princess Diana had to “internalize and deal with” the negative media coverage.