For Prince William, this emoji takes the crown.

While visiting Birmingham, England for World Mental Health Day with Kate Middleton Oct. 10, the Prince of Wales revealed which symbol he uses the most when texting.

"Is this a clean thing, or is this a family one?" William asked BBC Radio 1's Vick Hope and Jordan North before giving his answer. "I've been told not to say the aubergine, so I've got to pick something else. It would've been the aubergine, but I'm saying now—because I've got to be a little grown-up—it's the one where the eyes go up and down the mouth's out."

As for Kate's most-used emoji? It's certainly not the aubergine—a.k.a. the eggplant.

"Mine's probably going to be the heart," the Princess of Wales replied before providing another answer, "with then the crying emoji—the sort of like hysterical laughing when things have gone wrong."

The radio hosts couldn't get enough of William's cheeky response.

"He said the aubergine emoji!" Jordan said on their show Going Home With Vick and Jordan on Radio 1. "What is happening? He said the aubergine emoji! This is brilliant."

These weren't the only personal insights William and Kate shared with chatting with Jordan and Vick. In fact, the royals revealed their dinner plans and said they would probably choose curry. But when it comes to their meal preferences, William and Kate have to find a compromise as he noted he can't exactly handle the heat.

"I can't do too much spice. I start sweating," the prince noted. "It's unattractive." 

As for Kate, she shared, "I like the spice. I have to sort of cook the curry and then add the spice—extra spice—at the end." 

William added, "She has to bring it in gently because otherwise I get too sweaty. It's not a nice sight."

During their visit, the couple hosted a forum to talk about mental health and William spoke about the role humor can play.

"Humor for me is a big deal—I love to laugh," he said, per People. "You've got to look at the lighter things in life sometimes to feel good."