the human body.
It's not mentioned by name in the Constitution, but the U.S. Supreme Court has recognized a "right to privacy" - a right to be left alone.
It protects the intimate relations of fully consenting adults - straight or gay, married or single. So, with at least seven orifices per partner, the possibilities are just about endless.
Under the Ninth Amendment, your reproductive rights are fully protected as well.
The Courts have said what you do in your bedroom is nobody's business but your own - unless you happen to buy a digital video camera and post your adventures on YouTube.
Hint: You may want to go on a crash diet first, video adds 10 pounds to your appearance. Ready for your close-up?