Not everyone is given a chance to meet the royal family at certain events, so when Jon Hamm got the opportunity, he put his biggest smile on. However, despite his excitement, there were also rules that he needed to follow before shaking hands with the royals.

Earlier this month, the actor personally met Kate Middleton and Prince William at the premiere of his movie "Top Gun: Maverick," in London, United Kingdom.

Speaking to "The Tonight Show with Jimmy Fallon," Hamm revealed there are "guidelines that are not so many guidelines as hard and fast rules that you are made to follow" whenever someone is meeting with members of the royal family.

In a separate interview on "Live with Kelly and Ryan," the actor noted that meeting the royal family is "a little anxiety-producing" as their entourage gave them rules that they're meant to follow.

Hamm said people are being meant to address them as "Your Royal Highness," but if they offer their name, the public could use it, but they can't do it first.

"you can't offer your hand, they have to offer their hand. Then you have to bow, but you can't bow too low," he explained.

Upon meeting the Duke and Duchess of Cambridge, the actor was impressed by the Prince's custom shoes as he kept looking at them.

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While he was busy admiring the royal's shoes, his co-star Miles Teller was more distracted by Prince William's eyes.

"He geeked out a little on Prince William's eyes. I remember coming back afterwards, he's like, 'They're so blue. I got lost in his eyes,'" he added.

According to People Magazine, the monarchy has modern ways of greeting Queen Elizabeth II and other royal family members without "so much pomp."

Even though the British royal family's official website states that there are no "obligatory codes of behavior" when meeting the queen, a traditional form has been used over the past decades to avoid being rude.

Whenever a person meets a royal, they must shake hands when being introduced; men should do a slight neck bow, while women do a small curtsey.

When addressing royal family members, the correct formal address is "Your Royal Highness" as well as "Sir" and "Ma'am."

Middleton turned heads at the "Top Gun: Maverick" as she wore a dazzling black floor-length gown by Roland Mouret.

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