Credit: John Stillwell/WPA Rota

Kate's granny-in-law is a cut-up!

On Friday, Duchess Kate made her first official appearance in London since returning from the royal tour nearly two weeks ago.

Prince William's bride, 29, stopped by Buckingham Palace for a date with Queen Elizabeth II. The fellow royals accompanied one another to a brand-new, hugely popular exhibit (over 150,000 tickets sold!) spotlighting the April 29 wedding. See more photos of Kate and Queen Elizabeth II at the exhibition.

Kate, showing off her super-slim figure in a white dress, looked on at new displays featuring her iconic wedding dress (designed by Sarah Burton of Alexander McQueen), tiara, earrings, jewelry -- and even her wedding cake!

VIDEO: Relive every moment of the royal wedding

And the Queen, 85, showed where her grandson Willam, 29, got his wicked sense of humor. As she and Kate looked at the wedding dress, the Queen quipped of the display, mounted on headless mannequin, "Horrid, isn't it? Horrid and dreadful!"

As the duo toured the state rooms of the palace, the Queen added, "You've seen this already, so... you don't really want to see it again, do you?"