1. Unknown to the boss, many employees left work earlier than they were supposed to. They thought they had a good thing going until Bill became angry and rocked the boat by telling the boss what was going on.
2. Everyone is happy with the situation as it is. If you change it, you’ll be rocking the boat.

Compare to: upset the apple cart. The expression often describes a situation that becomes worse for the people involved when someone opens the situation to scrutiny. The expression suggests the idea that people who stand up or move about in a boat disturb the other passengers because the boat may capsize. It is frequently used as the negative command, “Don’t rock the boat. ”