When Prince William and Prince Harry speak about their childhood with Princess Diana, they often discuss her sense of humor and how she encouraged them to have fun. However, it appears Prince Charles had to pay the price for Diana’s desire for their sons to have fun.

Last year, Princess Diana’s personal trainer Carolan Brown told the Daily Mail that Princes William and Harry played a prank on Prince Charles that left him furious.

“One day, William and Harry let a stink bomb off in the hall after Diana had taken them to the joke shop, and then they let another one off in Charles’ office,” Brown recalled.

“He went absolutely mad, but Diana just laughed,” she added.

According to Princess Diana’s bodyguard Ken Wharfe, Prince Charles wasn’t the only target in William and Harry’s practical jokes. Wharfe revealed that Prince William channeled Diana’s mischievous side and played a risqué prank on his mother after she offered to wash her bodyguard’s shirt.

“Being flirtatious was part of her style and certainly an incident at her mother’s house in Scotland involving William showed that he was aware of this,” he explained.

When Wharfe saw Princess Diana the following morning, she wearing a towel while ironing his shirts. “William came in and said, ‘Oh why are you doing Ken’s shirts?’ and pulled the towel off her. She was totally naked, and I said, ‘William, that was stupid.’ William said, ‘I know Mummy likes you,’ and I said ‘William, Mummy likes a lot of people. Let’s not do that.’”

Despite what most would perceive as an embarrassing moment, Princess Diana reportedly laughed off the prank. “It all happened so quickly. There was a smile on Diana’s face. Whatever she was thinking, she had to see the funny side,” Wharfe said.

Although Prince William and Prince Harry enjoyed light-hearted moments with Diana, they were heartbroken over her death in 1997 and reportedly resented Prince Charles’ relationship with Camilla Parker Bowles.

In Penny Junor’s book “The Firm,” she revealed the boys struggled to accept Charles’ romance with Camilla.

“They loved their mother and are fiercely loyal to her memory – and know that Camilla was the cause of her terrifying unhappiness,” she wrote.

However, both Prince William and Prince Harry were present when Prince Charles married Camilla in 2005.

Princess Diana, Prince William and Prince Harry
Princess Diana is pictured with her sons Prince William (left) and Prince Harry on a skiing holiday in Lech, Austria, on March 30, 1993. Jayne Fincher/Princess Diana Archive/Getty Images