Prince Louis of Cambridge made his Trooping the Colour debut on Saturday, joining senior members of the royal family on the balcony of Buckingham Palace to celebrate Queen Elizabeth II's official birthday.
Mum Kate Middleton quickly copped the move and gently corrected her youngest child in a touching moment watched by the world.
And that wasn't all little Louis got up to on the balcony..
WATCH this video to see the tiny Prince's adorable royal wave knock Camilla Parker-Bowles' hat off!
Louis was the star of the show for his first appearance with big brother Prince George and big sister Princess Charlotte, while grandfather Prince Charles looked on with amusement as tiny royal rebel got up to mischief.
William and Kate were kept amused throughout the parade as Prince Louis waved vigorously to the London crowds and made confused faces at the aircraft flying overhead.
It was a big day out for the British royals with Meghan Markle making her first public appearance since introducing her first child royal baby Archie Harrison Mountbatten-Windsor to the world with a photo call at St. George's Hall in Windsor last month.
The Duchess of Sussex looked radiant in a navy dress and tailored cape by her royal wedding dress designer, Givenchy's creative director Clare Waight Keller, arriving at Buckingham Palace in a carriage with her husband Prince Harry, step mother-in-law Camilla, Duchess of Cornwall and sister-in-law Kate Middleton.
Also spotted on the Buckingham Palace balcony were recently married Lady Gabriella Windsor and her financier husband Thomas Kingston, Prince and Princess Michael of Kent, Prince Philip, Prince Andrew, Prince Edward and Sophie, Countess of Wessex, Princess Anne, Princess Eugenie of York and Jack Brooksbank, Princess Beatrice of York, Savannah and Isla Phillips and the Duke and Duchess of Gloucester.
But despite the happy occasion, new mum Meghan appeared uncomfortable, according to Express.co.uk's body language expert Judi James.
The analyst claimed the Duchess' demeanor showed signs of a rift between the houses of Cambridge and Sussex, adding Kate's posture was "slightly self-diminished".
Whispers of discontent began earlier this year with rumours of a falling out between Kate and Meghan.
But recent reports indicate the true source of tension lies between the Duke of Cambridge and the Duke of Sussex.
The sons of Princess Diana added fuel to the fire by splitting their joint charity, The Royal Foundation, which William and Harry founded together in 2009.
“A spokesperson has said they work on different issues now but they will come together for certain things,” royal commentator Angela Mollard revealed on the New Idea Royals podcast.
“I think this suggests more than ever that there really is genuinely a rift.”