Wikipedia, tonight:

Jester’s privilege is the ability and right of a jester to talk and mock freely without being punished. As an acknowledgement of this right, the court jester had symbols denoting their status and protection under the law: the crown (cap and bells) and scepter (marotte), mirroring the royal crown and scepter wielded by a monarch.

Martin Luther used jest in many of his criticisms against the Catholic Church. In the introduction to his To the Christian Nobility of the German Nation, he calls himself a court jester, and, later in the text, he explicitly invokes the jester’s privilege when saying that monks should break their chastity vows.