Its saying basically that there are hidden secrets underneath people. That every smile, nod or wave has a hidden agenda. It's like warning to be wary of who you trust.
Answer:
Eroison
Explanation:
Erosion is the process by which natural forces move weathered rock and soil from one place to another. Gravity, running water, glaciers, waves, and wind all cause erosion. The material moved by erosion is sediment.