Appearing on "The Tonight Show Starring Jimmy Fallon" on Wednesday night, the actor opened up about being seated next to the late Princess of Wales at the world premiere for "Back to the Future" back in 1985. While he says it should have been "the greatest night of my life," he remembers it now for all the wrong reasons.
"She was sitting next to me. The lights go down and the movie starts and I realize I am one fake yawn and an arm stretch away from being on a date with her, which is hilarious," he recalled.
"The movie started and also I had to go pee. And so for the rest of the movie, I'm sitting there, like, dying," he continued. "I can't say anything to her and I can't walk away from her because I can't turn my back on her. So it was just agony."
He said the night "could have been the greatest night of my life but it was just a nightmare. A pee-holding nightmare." Fox added, however, that Diana herself was "great," "sweet" and seemed to enjoy the movie.
Fox's appearance on the show comes after the release of the actor's new book, "No Time Like the Future." In it, he opened up about the new challenges he's faced in his battle with Parkinson's and his "second retirement."
"There is a time for everything, and my time of putting in a 12-hour workday, and memorizing seven pages of dialogue, is best behind me," 59-year-old Fox writes in the book. "I enter a second retirement. That could change, because everything changes. But if this is the end of my acting career, so be it."