The Great Old Churches Are Full of Porn
Much of the art made during the Italian Renaissance was specifically commissioned by the Catholic Church to adorn the walls of Catholic cathedrals for the everlasting edification of Catholic God lovers. And up until the mid-1500s, the Catholic Church was pretty cool with artists getting a free hand on their walls.
Sometimes "free hand" meant tastefully rendered imaginings of the heroes of the Bible. And sometimes "free hand" meant literally having a free hand to masturbate with after viewing said pictures.
Wait, What the Hell?
Renaissance artists often used their art to get their freak on.
At least until the Counter-Reformation, when the church put the kibosh on the flagrant display of holy genitalia and hired a loincloth painter to cover the most offending penis action, such as the scene above, from Michelangelo's "Last Judgment." Prior to the cover-up, Mr. Red Robe back there was full-on naked and looking down at the badonkadonk of St. Lady Gun, who was also naked. And considering her bent-over posture, it totally looked like he was getting some from the backside.
But the Catholic Church wasn't the only game in town, and plenty of other Renaissance artists used their prodigious talents to prove it. Once these guys were out in the secular world, things started getting explicit. Such as:
Snaky guy on girl.
School of Fontainebleau
Girl on girl.
Jusepe de Ribera