Don't shit in someone else's toilet

A term used for those who plan on going abroad. Don't always assume that the laws over there will be the same as in your home country, they may be different and you could get caught out. It causes terrible anxiety to get arrested or go through a judicial process in another country so be careful. A good example is if you plan on flying a drone in another country. The laws may be different and the foreigners may get more irate over it than those in your own country.

Person 1: I might fly my drone over Paris when I go.
Person 2: French law may be different, be careful. Don't shit in someone else's toilet!