The word sheeple is a pretty mean-spirited term. It's used by some critics to describe people whom they perceive as behaving in an overly meek and docile manner.
The word sheeple is a portmanteau of sheep and people. In general, sheep are thought of as being quite docile and easy to herd. They follow a shepherd, and they stick together, traveling the same path as the other sheep. The term sheeple emerged in the 20th century as a negative critique of mass consumerism and political conformity. Because it compares humans to livestock, especially in a way that suggests being overly simple, unquestioning, and conformist, it is considered an offensive term.