A reader writes:
A widely studied Spanish 16-century classic work of literature, Lazarillo de Tormes, was published anonymously in the 1550s and features as protagonist an errant boy who is taken in by various masters, priests and father figures. A short episode that was later censored by the Inquisition in 1573 features Lazarillo with a Mercedarian priest/friar. The boy leaves him in a hurry, explaining mysteriously "...so for this and other reasons which I shall not mention, I left him (y por esto y por otras cosillas que no digo, salí dél)
In the academic article mentioned below the authors cite a popular saying from those years in Spain, the time of the Counter Reformation: "Cuando vieres a un fraile de la Merced, / arrima tu culo a la pared" i.e. "Whenever you see a Mercedarian priest, press your ass against the wall."
The story features other types of corrupt clergy in various chapters, including those who keep women on the side, etc. But this one with the Mercedarian priest has by now been accepted as an obvious between-the-lines reference to pedophilia.
Bussell Thompson, B. and J.K. Walsh. "The Mercederian's Shoes (Perambulations on the Fourth tratado of Lazarillo de Tormes)." MLN 2 (1988): 440-48.