There is an old myth that lemmings, these rodents, will occasionally, in massive hoards, jump off cliffs into the water and their death. It’s quite a grim scene.
This scene of following the leader is often cited as an example in behavioral psychology as a danger in mass-conformity and herd-following.
There’s only one problem: lemmings don’t conduct group suicide.
Lemmings multiply fast and they need to migrate after a huge population boom every 3-4 years to find more space. Lemmings can swim, and may try to cross rivers or bodies of water in search of a new home. Inevitably, some will drown.
It would be quite curious if lemmings did commit mass suicide, still, this story is an irresistible metaphor for decision behavior and the dangers of conformity and mass-herd following. You never know who might be leading you off a cliff.