Mass Moments recounts H.L. Mencken's arrest on Boston Common on April 5, 1926, because his American Mercury magazine ran a story about a prostitute that offended Boston's Watch and Ward Society:

... When the Watch and Ward Society immediately banned the issue as obscene, Mencken boarded a train for Boston. Once in the city, he orchestrated a meeting with John Chase, the Society's director, at the "Brimstone Corner" on Boston Common. With police, press, and a rowdy crowd of students on hand, Mencken offered Chase a copy of the magazine. Chase gave him a half-dollar piece (which Mencken bit for effect). Within minutes, the Boston vice squad placed H.L. Mencken under arrest. ...

H/T: Boston Metblogs.