LeBron James may refer to himself as the “King”, but that doesn’t count for anything when you meet a real life princess.

Prince William and his wife Kate took in a Cleveland Cavaliers NBA game in New York on Tuesday night.

Afterwards, things got awkward.

James, the biggest star in the basketball world, violated royal protocol when he posed for a photo with the Duke and Duchess.

James put his arm around Kate, which in case you are unaware is simply unacceptable.

When one meets a royal, there is a “no touch” rule.

Indeed, Kate did appear uncomfortable.

Bad boy, LeBron.

But the King is not the only one who has overstepped the mark.

In April, Australian Prime Minister Tony Abbott put his hand on Prince William’s back in Federal Parliament.

In 1992, another Aussie politician got it wrong, with Paul Keating placing his hand on the Queen’s back.

America’s First Lady Michelle Obama also put her arm around the Queen in 2009.

While in 2007, the late actor Mickey Rooney took it to a whole new level, planting a kiss on the Queen’s hand.

These are the rules, according to the BBC:

When meeting a royal, there are rules about who can speak first, where to look, what to call them, how you should stand and when you should sit. It is a mysterious business to the uninitiated.

But it stems from a time when monarchs were accorded an almost divine status and had to be treated accordingly.

“From medieval times, monarchs were divinely appointed to rule by God, so they were kind of seen as gods, so they demanded to be treated as gods,” says Dr Kate Williams, a historian at London’s Royal Holloway university. “They are treated as people set apart from the rest of us, so primarily what it is creating is distance and grandeur.”

It’s too bad LeBron and Co. weren’t made aware of them earlier.