King Charles' Funny Side: Monarch's Comical Quirks 'Used to Get Him Mocked'

King Charles III is more well-known for his often fiery temper and "grouchy" looks in public, but His Majesty also has a funny side. The monarch's sense of humor is endearing to those around him, however, it "used to get him mocked," as well, according to royal author, Robert Hardman, in his new book, Charles III: New King. New Court. The Inside Story.

"He does love being out and about in the countryside," Hardman told an outlet. "He’s always disappearing, and he’s got a particular thing at the moment with planting trees. He’s obsessed with it. He’s always liked planting trees. He used to get mocked for it slightly because whenever he planted a tree, he’d always shake one of the leaves by the hand and say, 'Good luck, tree.'"

He continued: "The tree planting has gone up a notch since he became king," Hardman shared. "He is now planting so many trees. I talked to one of his staff, and he said, 'Well, we often joke, Where’s the king? He is probably planting trees.' And it turns out... he is planting trees. He’s not at his desk; he’s out in the garden."

The tome also revealed that Charles III is a stickler for maintaining a strict exercise regimen that he developed during his time in the Armed Forces, all the way back in the 1970s. Before his recent successful prostate operation at age 75, the King's only other health concern was a sporting accident that broke his elbow and required surgery in 1990.

But Hardman's revelation from staff that sticks out the most is His Majesty's peculiar and "freezing" habit that even makes Queen Camilla frustrated.

The King prefers to keep windows open in whatever palace or castle he is staying in for "fresh air," ...even during the frigid winter months. The author shared how the Queen will quietly go behind her husband and shut windows as to keep the internal temperature from hitting the freezing mark.

The monarch of 14 nations apparently likes to poke fun at himself as well by wearing a tie that is printed with small T. Rex dinosaur symbols, which is a pun based on his Latin initials.

"His favorite [tie] has a little T-Rex motif on it," Hardman dished. "I thought, 'That’s a bit odd. I keep seeing this tie with a dinosaur on it...' Of course, his cipher says, C. Rex, Charles Rex. So, I think he’s having a little joke about being king with his tie. But he’s in a good place. He’s a happy monarch."

"Rex" is Latin for the word king, and always follows a male monarch's name in official royal statements.

Fox News spoke with Hardman.