Prince William and Princess Kate are certainly reserved in public, but that doesn't stop them from doing PDA behind closed doors.

This usually takes the form of a hand on their spouse's back or arm or a loving look, but 2023 has been full of surprises for the royal couple.

Indeed, at the King's Scottish coronation this week, the Princess of Wales was seen secretly "butt-pumping" her husband. If you recall, she also made a cheeky gesture at the BAFTAs in February.

In any case, following this incident and their behavior throughout the day, body language expert Judy James compared the Welsh couple's public behavior to that of the King and Queen.

"The King and Queen are more like ventriloquists, mumbling in a way that doesn't look like actual conversation, but at events like this, being able to mumble may feel comfortable to them," James explained to the Mirror.

"Their speech often overlaps, which again suggests that it is a tool of mutual support and comfort rather than a way to converse verbally. There is no eye contact either.

This is a really nice custom, but James feels that the Welsh couple are a bit more direct in their public displays of affection.

"William and Kate always signaled that they listen carefully to each other, and here they performed their signature ritual of adding either a touch or a truncated touch to communicate in both verbal and nonverbal gestures that indicate emotion.

"Kate also made her now signature spanking gesture, and couples tend to use eye contact and exchange smiles when speaking."

OK, I don't know if doing something twice actually qualifies as a "signature," all I know is that it's a very fun move by Kate and I enjoy her sense of humor.