“In Indiana and Tennessee, the crime of public nudity is defined to include (emphasis added) the showing of the human male or female genitals, pubic area, or [Indiana only:] buttocks with less than a fully opaque covering, the showing of the female breast with less than a fully opaque covering of any part of the nipple, or the showing of covered male genitals in a discernibly turgid state.

So if you’re in a public place and find yourself with an erection, you are legally obligated to sit down until it goes away.”

http://volokh.com/posts/1116879770.shtml
http://volokh.com/posts/1116879770.shtml
http://volokh.com/posts/1116879770.shtml