Wis. Stat. § 939.61: Penalty when none expressed.

(1) If a person is convicted of an act or omission prohibited by statute and for which no penalty is expressed, the person shall be subject to a forfeiture not to exceed $200.

(2) If a person is convicted of a misdemeanor under state law for which no penalty is expressed, the person may be fined not more than $500 or imprisoned not more than 30 days or both.

(3) Common law penalties are abolished.