The future king, 41, was responding to a question about his favourite emoji when he made a slightly NSFW joke, first asking if it was "a clean thing or a family one?".
He then revealed his most-used emojii would be the eggplant [aubergine]: which is most known for having sexual connotations, and commonly used to depict male genitalia.
“I’ve been told not to say the aubergine, so I’ve got to pick something else," Prince William said.
"It would have been the aubergine, but because I’ve got to be a little grown up," he continued, as Kate Middleton laughed. "It’s the one where the eyes go up and down and the mouth’s out.”
The radio hosts later joked about William's 'dirty mind' describing his answer as 'brilliant'.
As for Kate's response, she said her most-used emoji was the heart or the crying emoji.
“The sort of like ‘hysterical laughing’ when things have gone wrong,” she said.
Prince William's cheeky admission comes after it was revealed he and Kate, 41, have some cute pet names for each other behind closed doors.
In a new book Gilded Youth: An Intimate History of Growing Up in the Royal Family by Tom Quinn, palace staff said that William sometimes called Kate 'babykins' while she stuck to a more traditional 'babe' or sometimes a joking 'baldy' to refer to her husband.
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