Cheeky cheeks seen around the world at last night's BAFTAs: we've been seeing more and more Prince and Princess of Wales PDA lately. Dressed in ALEXANDER McQUEEN and wearing long opera gloves, Kate playfully smacked William's butt.

The Mirror quoted body language expert Judy James as calling Kate's spanking a "sexy reprimand," and lip-reading expert Jeremy Freeman described the moment just before the surprise PDA.

William and Kate were walking down the red carpet when something caught Kate's attention and she turned her head dramatically to see what was going on behind her. She turned back to William, who did not turn around, and they appear to have exchanged a few words.

"How did I miss it? Kate asks her husband, according to Freeman.

"What? William answers before Kate replies, "Stop ignoring me." Before Kate can spank his ass, he asks, "Ignore who?

James, an expert on body language, describes this moment: "She was just trying to get him to stop ignoring her. She then pushes her right hand toward William, seemingly as a signal to hold hands. William mistakenly leans in, suggesting that he is expecting the same lovey-dovey whispering as before, and raises his hand as he brings his head closer, missing Kate's offer. Kate then "rewards" William with a spanking. In other words, this serves as a sexy ritual or thank you, as well as a small reprimand for missing her cue"

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This is the couple's first return to BAFTA in three years, and we won't soon forget it.