At the age of nine, the comedian and actor was given the role of a shepherd in his school nativity play, a production which went badly wrong after the boy playing the lead role of Joseph was taken ill and began vomiting on the child playing the Virgin Mary.
"I was at boarding school in Wolverhampton for my first Nativity, and must have been about eight or nine," the veteran comic tells British magazine SAGA.
"It was my debut stage role and I was one of the shepherds abiding in the fields. The hall was packed with proud parents, but what made my first experience of show business so memorable was the unexpected sight of Joseph suddenly throwing up all over the Virgin Mary."
The British comedy icon admits his troubling early experience with the story of Jesus' birth may have influenced him later in life when he and his fellow Monty Python members made their film The Life of Brian, a satire on the life of the Christian messiah.
"It was just so great, out of the blue, and nobody knew what to do," he says. "We found many versions of this primal Nativity scene, and virgin births, when we were researching religions prior to writing The Life of Brian.
"But we never found anything where the stepfather of God threw up over His mother. I think Joseph's reaction to the Nativity story has clouded my impression of the whole business of religion ever since."