Anyone who has children or has been around them for any length of time knows that a child's behavior on any given day is unpredictable. Imagine being Princess Catherine, and having three children under the age of 10, on the world stage at a royal event. (Prince Louis is four and has already had a long weekend of sugar overload.)

According to the new book "Gilded Youth: An Intimate History of Growing Up in the Royal Family" (opens in new tab) (and appears on Hello) and after speaking with former employees of the royal family, author Tom Quinn learned that Kate had a "secret code" that she frequently used on her children Prince George, Princess Charlotte, and the aforementioned Louis.

"For example, when Prince Louis misbehaved by sticking his tongue out at his mother at the late queen's platinum jubilee, Kate's reaction was praised by a team of expert commentators," Quinn wrote. She apparently used a secret code to calm the children down."

The book quotes a former royal staffer as explaining that the four-word phrase was a sign for Kate to behave and stop fooling around with her children, and that if they didn't listen, there would be consequences at home. (Do you hear these words coming out of Kate's mouth at the moment the above photo was taken?

One of Kate's biggest concerns in her work as a royal is early childhood development, and one can imagine that "let's take a break" is not four words she strung together lightly and without thought; as she herself said in 2019, when it comes to parenting, she "knows how important it is that we do it know how important it is to do it right."