Queen Elizabeth II may be the world's longest reigning monarch, but that doesn't mean she won't slap the taste out of your insolent mouth. At least according to fellow British queen Elton John.

In his new memoir, Me, the legendary pop star recounts a time that the Queen put her hands on her nephew Viscount Linley. During a party, Her Royal Badness had asked him to watch his sister, Lady Sarah Armstrong-Jones, who was feeling under the weather. Linley resisted because he didn't want to miss out on the festivities, and so, John writes:

“When he [Linley] repeatedly tried to fob her off, the Queen lightly slapped him across the face, saying ‘Don’t’ – slap – ‘argue’ – slap – ‘with’ – slap – ‘me’ – slap – ‘I’ – slap – ‘am’ – slap – ‘THE QUEEN!'”

Linley then did as he was told. Naturally.

When Liz saw that Elton had witnessed the whole thing, he says she simply winked at him and walked away. “I know the Queen’s public image isn’t exactly one of wild frivolity, but," he writes, "in private she could be hilarious.”

Well, if anyone could wax lyrical about the Mother of the House of Windsor's cheekiness, it's Sir Elton John, as he and the Queen go way back.

Here he is having a royal kiki with her in 1977 at her Silver Jubilee, and again in 2012 at her Diamond Jubilee.

Turns out Saturday nights are all right for slappin'.