Ah, for the Gracious Courtliness of the Past:

E.P. Thompson's chapter on "Rough Music" in Customs in Common (1991), reports on this incident:

The Reverend Charles Jeffrys Cottrell, JP, the Rector of Hadley in Middlesex, was driven in 1800 to take legal action when he received in the post a portrait of a gibbeted parson with his genitals exposed, inscribed "O what a miserable Shitting Stinking Dogmatick Prig of an April fool I do appear."

This stemmed from a tax dispute, of course.