They're the perfect pair! During their latest royal outing on Tuesday, July 10, Kate Middleton and Prince William joined members of the royal family at London's Westminster Abbey to celebrate the 100th anniversary of the Royal Air Force. But during the church service, William seemed to be very distracted by something funny that caught his attention.

In an Instagram video posted by royal fan account @hrhprincgeorge, the doting dad can be seen trying to stop himself from laughing during the serious event — and the gaffe soon caught his wife Kate's attention. But once she looked over to him, William shyly tried to hide his giggles until he finally turned to his spouse and continued laughing, which prompted Kate to crack her own smile.

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With Kate's help, William quickly recollected himself, but it's still unclear what caught the Prince's attention at the event in the first place. Royal fans later came up with their own predictions about what started William's uncontrollable laughter.

"He's thinking about what Charlotte said to [the] photographers, "you're not coming," so funny and typical of little ones," one fan hinted on Instagram about Prince Louis' royal christening. Another person then said, "I think he's remembering when he was caught sleeping in [the] Anzac day church service. Just three days after [the] birth of Prince Louis." Whatever it was, it's great to see Kate and William getting along so well!

Meghan Markle and Prince Harry also attended the royal service and Meghan stunned in a black dress designed by Dior. Kate instead opted for another Alexander McQueen outfit and sported a matching hat as well. The royal family has been known to spend a lot of money on their attire for official royal outings.

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Fans were quick to notice that Meghan's dress at the RAF centenary looked a lot like her Givenchy wedding gown, which also featured a boatneck and long sleeves. Meg allegedly spent around $440,000 on her ceremony dress and it has been reported that her royal wardrobe since marrying Harry has cost about $1 million.

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