“What’s this black stuff?”
“It’s seaweed.”
“Oh, okay. I’ll try it. Wow, it tastes kind of fishy!”
“I can’t believe you ate that.”
“When in Rome, do as the Romans do. You should try it too. It’s not bad!”

This phrase can be generalized to any place, such as another country or a friend’s house. When you are at home, you can follow your own preference, but when you are somewhere else, you must sometimes adjust your behavior to match others.