Wacky fun with the Religion of Peace
Falling on the 10th of Muharram, the first month of the Islamic lunar calendar, Shia Muslims mark the death of the Prophet Muhammad's grandson at Karbala with mourning rituals and plays re-enacting the martyrdom.
Men and women dress in black and parade through the streets slapping their chests and chanting.
Some Shia orders flagellate themselves with chains and blades to emulate Hussein's suffering - though this is frowned upon by others.
Also, take a look at this thread from Free Republic to get an idea how sick and weird this is.