Chicken Little

The phrase "jumping on the bandwagon" describes the actions of a person who joins in a cause without really considering whether it is the right thing to do.  As exemplified in this cheerful retelling of a classic fable for children, this may not always be the wisest choice. 

Believing in a foolish superstition, Chicken Little is convinced that the sky is falling.  In her distress, she convinces a number of other animal friends that this is indeed the case.  One after another, the animals join Chicken Little, soon forming a frantic pack.  Fortunately, Chippy Chipmunk steps in with wise intervention.  What follows confirms the importance of critical thinking and the possible dangers of gullibility.