mouton de Panurge

Etymology
From a character, called Panurge, in the book by. In the story, Panurge buys a sheep from a vendor and in revenge throws it into the sea. The other sheep in the flock, and the vendor himself who has jumped on the back of the final sheep, instinctively follow suit and drown in the sea too.

Noun

 * 1) lemming, sheep one who follows a group without thinking for himself