The royal children have a history of goofing off at public events (see Princess Charlotte at the royal wedding and Prince George's I-don't-care-what-you-think faces). At today's Trooping the Colour, one royal child followed suit and channeled Prince Harry, who posed exactly the same way at the 1988 Trooping the Colour. FYI, he was only four years old at the time.
Here's Princess Charlotte posing for the paparazzi at the royal wedding less than a month ago (is there a tongue game I'm missing out on?):
This new little girl who stole the show is Isla Phillips, Queen Elizabeth's great-granddaughter who's 16th in line for the throne. Her parents are Peter and Autumn Phillips—Peter is Princess Anne's son. Peter and Autumn's first child, Savannah, was born in 2010 and is seen next to her sister. She quite literally told Prince George to be quiet while singing.
Isla may be taking the lead in goofing off, but Savannah just SHUT. IT. DOWN. Prince George doesn't even seem mad about it.