A person who makes any open and indecent or obscene exposure of his or her person, or of the person of another, is guilty: For the first offense, of a gross misdemeanor. For any subsequent offense, or if the person has previously been convicted of a sexual offense for a category D felony. A person 18 years of age or older who commits an act of indecent or obscene exposure in the presence of a child or a vulnerable person is guilty of a category D felony.