Kate Middleton Doesn't Believe Prince William Could Run a Marathon, Plus 3 More Times She (Lovingly) Shut Him Down

Duchess of Cambridge is one sassy royal

Who knew?! Kate Middleton has a sassy side. 

It's no secret that the Duchess of Cambridge and Prince William love poking fun at each other, but over the years, Kate has proven that she's got some serious zingers and one-liners up those Jenny Packham-designed sleeves of hers. 

Take for example, the time when Prince George and Princess Charlotte's proud mama scoffed at the thought of her husband running a marathon. The pair stepped out on Tuesday to support their Heads Together mental health campaign, and during the event, British television personality Sean Fletcher told reporters that Kate has major doubts about William's 26-mile aspirations. 

"I chatted to Prince William, and he has promised that he will run a marathon in Kenya sometime," he shared, before adding, "Then I spoke to Kate and she said, ‘I'll believe it when I see it.'" LOL. You tell 'em, Kate.

Then there's the unforgettable moment when Kate addressed what many know to be true (but never dare discuss out loud): Prince William's thinning hair. 

During a shearing demonstration at the Royal Easter Show in April 2014, Kate pointed out that her leading man could benefit from a toupee made from an alpaca's coat of hair. 

"The Prince was interested in the alpaca and as I showed it to them, the Princess said he should put it on his head," farmer Lyn Crejan dished to the media. "She said, 'You need it more than me,' and pointed to his head and he laughed."

Fans of the royal family know Kate is a total sports nut, and in 2014, she put her sailing skills to the test in a competition against none other than Prince William. Surprise to no one, Kate took to the water like a duck and dominated her opponent. 

Prior to the heated race, William predicted there would be "healthy competition" between him and his wife, but Kate (with her unmistakable competitive streak) knew otherwise.

"Take care!" she  teased her husband with a pat on the back. "Yeah, see you later," he quipped.

Earlier this year, Kate took yet another playful jab at William while raising awareness for Heads Together at a local school. Reminiscing about their teenage years, William shared, "Sometimes I still feel like I am 16, to be honest sometimes I still act like I am 16."

Kate didn't hesitate to chime in, "I still think you're 16," to which William responded, "Yes, Catherine often tells me that."

Hey, no one ever said a great sense of humor hurt a relationship.