There's a reason why Queen Elizabeth II is affectionately known as "the boss."

Prince William, second-in-line to the British throne, was reminded who is in charge by his grandmother, Queen Elizabeth II. The incident occurred at last weekend's Trooping the Colour while William was bending down on the Buckingham Palace balcony to talk to his son, Prince George.

In the exchange, which was caught on camera, Her Majesty was seen reprimanding the Duke of Cambridge, 33, by saying, "Stand up, William."

William, who calls the monarch "Granny," and George who refers to her as "Gan Gan," knew Her Majesty meant business.

The priceless reaction of 2-year-old Prince George, who put his hand on his face, was the icing on the cake.

William's younger brother, Prince Harry, also took note. Harry, 31, was standing behind William and next to Princess Kate and 1-year-old Princess Charlotte.

Trooping the Colour is the annual tradition to celebrate Queen Elizabeth II's official birthday.