I'm looking for a non-vulgar word or short, succinct phrase to describe group behavior wherein all of the individuals are making the same stupid choice. The vulgar "clusterfuck" is close. Acting like "lemmings" has some of the connotations I'm looking for as well.
Example: The other day I drove to pick my son up at school. As usual, there was a traffic jam. On this day, it was made worse by the fact that a dozen people ignored the empty parking spots along the curb and instead waiting in line behind each other, causing a jam which spilled beyond the intersection, blocking traffic on other streets. It was an example of one person after another making the same stupid choice, rather than thinking for themselves. The situation was a real XXXX.
EDIT: As is often the case with English (maybe all natural languages?), the answers have provided multiple ways to say this, with multiple fine shadings of meaning. Thank you all. How do I fairly select only one answer as the answer, when several work well?