She and her sister once partied incognito in the streets of London.

Elizabeth and Margaret got their parents' permission to join the massive crowds celebrating the end of World War II on May 8, 1945. The queen has recalled the evening as one of the most memorable in her life. 

"I remember lines of unknown people linking arms and walking down Whitehall, all of us just swept along on a tide of happiness and relief," she said in 1985, according to the BBC.

Elizabeth and Margaret's escapade has even been dramatized in a film called "A Royal Night Out."