So fans have never been more surprised when Prince William opened up about his very cheeky messages to his wife. The couple were taking part in Radio 1's Going Home show as they hosted a forum in Birmingham to mark World Mental Health Day when they were asked what emojis are their most commonly used – and while Kate's was romantic, William's was much more saucy!
"Is this a clean thing or is this a family one?" he joked to radio hosts Jordan North and Vick Hope. "I've been told not to say the aubergine so I've got to pick something else. It would have been the aubergine but I'm saying now – because I've got to be all grown up – it's the one where the eyes go up and down and the mouth's out. What's that one? The slightly crazy one."
Showing off her humorous side, Princess Kate admitted: "Mine’s probably going to be the heart with then the crying emoji. The hysterical laughing when things have gone wrong."
A shocked Vick couldn't help but comment on William's choice, joking: "He’s got a dirty mind."
Humour is actually one of the secrets to their happy relationship, William admitted when they got engaged in 2010. "Obviously we both have a very fun time together, both have a very good sense of humour about things, we're down to earth, we take the mickey out of each other a lot, and she's got plenty of habits that make me laugh that I tease her about," he said.
How did Prince William and Princess Kate meet?
Their love story began in 2001 when they met at the University of St Andrews. They both lived at St Salvator's Hall residence, but it wasn't until the following year that romance blossomed after Kate took part in a charity fashion show.
The Prince paid £200 for a front-row ticket and he began to see Kate in a different light after watching her sashay down the catwalk in a bikini and a sheer dress.
William and Kate's friendship turned romantic and the first photos of the couple were published in April 2004 when they enjoyed a ski break in Klosters.
When did Prince William and Princess Kate get married?
Following an on-off relationship, the Prince proposed with his late mother Princess Diana's sapphire diamond ring which Kate proudly showed off during their engagement photocall in November 2010.
They got married at Westminster Abbey in April 2011, with Kate stepping out in a lace Alexander McQueen wedding dress for her ceremony before changing into a strapless embellished gown for her evening reception, adding a modest fluffy jacket over her shoulders. Meanwhile, William wore his red military uniform, which was not his first choice of outfit.
The couple are now parents to three children: Prince George, Princess Charlotte and Prince Louis.