The 3rd amendment is that soldiers can't live in people's homes unless the owner consents to it. I think it goes back to the war where they would just go into any home and live there.

https://en.wikipedia.org/wiki/Third_Amendment_to_the_United_States_Constitution

Edit: wait this is the 4th I was reading the other comment when searching

Edit 2:

places restrictions on the quartering (the placement and/or sheltering) of soldiers in private homes without the owner's consent, forbidding the practice in peacetime

Original comment about the 4th:

It prohibits unreasonable searches and seizures and sets requirements for issuing warrants