Rather than calling Camilla Parker Bowles, their step-grandmother, "Grandma," "Granny," or "Nanny," Prince William and Kate Middleton's children call her "GaGa," something she made sure to tell pop star Lady Gaga when she met her at the 2016 Royal Variety Performance, according to The Sun.

It turns out that's the name her grandchildren call her, too. "My own grandchildren call me GaGa," Camilla told The Daily Mail after the birth of Prince George (via The Mirror). "I don't know if it's because they think I am! It is funny but is still very sweet."

Of course, that's not the only endearing nickname that younger members of the royal family have had for their elders. Queen Elizabeth has been called Lilibet since she was a child and is still called that by close family members. Even her great-granddaughter, Lilibet Diana, was named for her. 

When Prince William was small, he couldn't say the word "Grandma," so he called the queen "Gary," earning her a new special nickname between herself and her elder grandson

William and Kate's little ones have a special name for Prince Charles, too: They call him "Grandpa Wales" since Charles is, after all, the Prince of Wales. 

That type of nickname apparently isn't so unorthodox within the family. Queen Elizabeth herself called her grandfather King George V "Grandpa England" (via The Mirror).