Kate takes controls in fighter jet
It was an offer the Duke of Cambridge probably thought his wife could not refuse - jumping in the back seat of his fighter jet.
As a former RAF search and rescue pilot, William had the experience to take on the sophisticated aircraft - despite it being parked up.
But Kate had other ideas and deftly climbed into the cockpit of the Super Hornet jet during a visit to the Royal Australian Air Force (RAAF) base Amberley near Brisbane.
The Duke's smooth line to his wife: "Do you fancy jumping in the back?" had fallen on deaf ears.
She was not about to miss the opportunity to see for herself the multimillion-pound plane's mesmerising array of controls.
Wearing a white LK Bennett dress decorated with blue poppies, Kate climbed into the cockpit lifting one leg, then the other, mindful that her dress should not rise up too far.
William had to be content with being a back seat driver and sat behind his wife.
But at the end of the day, the couple sat side by side after they flew back to Sydney and headed out to relax watching a game of rugby.
Sipping lager and sitting between his wife and adviser Sir David Manning, William had put on his glasses to see the New South Wales Waratahs take on the Blue Bulls at the Allianz Stadium.
It is believed to be the first time the Duke and Duchess had spent a night away from their son Prince George attending a public event, during their tour Down Under.
The royal couple's visit to RAAF Amberley also saw the Duke and Duchess acknowledge Australian servicemen killed in recent conflicts.
They spent some private time with the relatives of four Australian servicemen who lost their lives in the Middle East.
William and Kate met the families of Lance Corporal Stjepan "Rick'' Milosevic, Trooper David Pearce and Private Matthew Lambert, who were all killed in Afghanistan, and Flight Lieutenant Paul Pardoel, who died in Iraq.
They spent about 10 minutes privately chatting to the relatives before moving on to a reception with veterans and their families.
Speaking ahead of the visit, Air Commodore Tim Innes, Senior Air Force Officer at RAAF Amberley, said the meeting would mean much to families still struggling with an enormous sense of loss.
He said: "That's an extremely important point about the visit. That is a big part of why they are visiting the base - to honour those fallen and those who made a sacrifice in Afghanistan and other conflicts around the globe.''
In a reception in the officers' mess, the Duke and Duchess met RAAF Amberley personnel, veterans and their families.
William singled out two-week-old baby Kora Riordan, commenting on her full head of hair.
Kora's father, Corporal Leon Riordan, said: "He joked about Prince George not having hair and that he had taken after his own genes."
Later the royal couple attended a reception in Brisbane hosted by Queensland Governor Penelope Wensley and Premier Campbell Newman.
There was a notably large security presence in the centre of the city and an Aboriginal demonstration across the road from the venue, the Brisbane convention and exhibition centre, was well policed.
The royal couple ended their day in Brisbane by going on a walkabout along the city's South Bank.
Thousands of people lined crash barriers and William and Kate were faced by a sea of camera phones and outstretched hands.