According to legend, an English woman, educated in Mainz, dressed as a man and, due to the convincing nature of her disguise, became a monk under the name of Johannes Anglicus. She was elected after the death of Pope Leo IV (term January, 847 - July 17, 855) at a time when the method of selecting popes was haphazard. She took the name Pope John VIII.
She was sexually promiscuous and became pregnant by one of her lovers. During an Easter Procession near the Basilica of San Clemente, over-enthusiastic crowds pushed around the horse which was carrying the Pontiff. The horse reacted, almost causing an accident. The trauma of the experience led "Pope John" to go into premature labour.
Pope Joan was dragged feet-first by a horse through the streets of Rome, and stoned to death by the outraged crowd. She was buried in the street where her identity had been revealed, between the St. John Lateran and St. Peter's Basilicas. This street was (supposedly) avoided by subsequent papal processions - though when this latter detail became part of the popular legend in the 14th century, the Papacy was at Avignon, and there were no papal processions in Rome.
Joan was reportedly succeeded by Pope Benedict III, who reigned only briefly but made sure that his predecessor was omitted from the historical record, in an act of damnatio memoriae. Benedict III is otherwise considered to have reigned from 855 to April 7, 858. Joan's ordinal name was later assumed by another Pope John VIII (term December 14, 872 - December 16, 882).
Supposedly, since her time, any candidate for the pope undergoes an intimate examination to ensure he is not a woman (or eunuch) in disguise. This involved sitting on a chair which has a hole in the seat. The most junior deacon present then feels under the chair to ensure the new Pope is male: "And in order to demonstrate his worthiness, his testicles are felt by the junior present as testimony of his male sex. When this is found to be so, the person who feels them shouts out in a loud voice
testiculos habet ("He has testicles") And all the clerics reply
Deo Gratias ("Thanks be to God"). Then they proceed joyfully to the consecration of the pope-elect"
