idiot brigade

Occurs mostly in interstate driving, when vehicles line up next to each other in parallel lanes, and then go the exact same speed, usually slow, so that nobody behind them can pass them or go any faster. This leads to an angry pileup of slowly moving traffic, which is referred to as an idiot brigade.

Frequently involves semis.

This phenomenon most often occurs on 2 lane highways, but has been known to occur across 3 or more lanes when idiots are very determined or exceedingly oblivious.