What is Public Indecency?

Legal Definition
This phrase has no fixed legal meaning, is vague and indefinite, and cannot, in itself, imply a definite offence. The courts, by a kind of judicial legislation, in England and the United States, have usually limited the operation of the term to public displays of the naked person, the publication, sale, or exhibition of obscene books and prints, or the exhibition of a monster,--acts which have a direct bearing, on public morals, and affect the body of society. The Indiana statute punishing public indecency, without defining it, can be construed only as that term is used at common law, where it is limited to indecencies in conduct, and does not extend to indecent words. McJunkins v. State, lO Ind. 140.
-- Black's Law Dictionary