It's apparently illegal in Michigan to swear in front of women and children. Also, a good one: If you plan to bath in public in Rochester, MI, your bathing attire must be inspected by police beforehand.
It is illegal to eat peanuts on the grounds, but outdoor, of a courthouse on Wednesdays in (i believe) Wisconsin.
Dumb Laws, Stupid Laws: We have blue laws, old laws, and just plain weird laws!