What the heck.
So this is an illustration of a pope (Innocent X, to be exact), who is having his testicles examined by a cardinal to make darn tootin’ certain that the newly-selected leader of Christendom is a man. Made in 1645, this print testifies to a long-lasting legend that all popes had to undergo this ritual checking, and that there was even a special seat with a hole in it created for this task: the _sedia stercoraria_ or “dung chair”.
“Duos habet et bene pendents,” would proclaim the cardinal after the testicle-check, according to one account: “he’s got two and they dangle nicely”.
Why so eager to establish the Pope’s cojones?, you may be asking yourselves? Turns out, there was a popular legend that got going in the 13th century that a woman had tricked her way into becoming a pope. She was often called “Pope Joan,” and Medieval accounts often state that she wormed her way into the Papal Curia through her sharp intellect, buoyed by her male lover. Often the accounts state that Pope Joan’s biological sex was only discovered after she gave birth on a street between the Lateran and St Peter’s. Sources disagree about what happened after: imprisoned or killed are two renditions.
Pope Joan seems not to have existed, according to current scholarly consensus. But Medieval and later Europeans thought she had. Enough to engineer the ancillary legend about the sedia stercoraria.
That is at least one explanation for the Papal ritual.
Sources: “‘The boldest and most remarkable feat ever performed by a woman,’: firey Joanna and the Siege of Hennebont, medievalists.net. Wikipedia