It's the custom in majority-Muslim countries for followers of Islam to demonstrate their piety by converging in the streets to pray. This has two effects - it allows Muslims to show that they are faithful, and it keeps non-Muslims aware of their inferior status.
For, you see, during that time, non-Muslims are pressured to stop all activity and commerce. If they continue working, or selling anything, they are often targeted by Muslims, and, often, the business is trashed by the "outraged" Muslims.
Furthermore, by moving their prayers to the streets, they maximally inconvenience the non-Muslim population. They arrange their prayer rugs to impede foot and auto traffic, thereby forcing the non-Muslims to stop their lives for that time, too.
Shown below is a video of that custom in France from the JihadWatch site. The deliberate tactic is becoming increasingly common on the streets of Paris and other parts of France where Muslims have settled.
Will it be coming soon to an American city near you?