Homonym: thin ice (Precariousness)
"Thin ice" refers to a layer of ice that is not thick enough to support weight safely. It can form on lakes, rivers, or ponds during cold weather, and its stability can vary based on temperature, water currents, and other environmental factors. Walking or driving on thin ice can be dangerous, as it may crack or break, leading to falls into cold water.
In a metaphorical sense, "thin ice" describes a risky situation where someone is in a precarious position, often due to poor decisions or behavior. For example, a person might be on thin ice at work if they consistently miss deadlines or fail to meet expectations, putting their job security at risk.