Al-Qaeda is the name of a terrorist organization known for being militant and religious extremists. The group appeared in "Osama bin Laden Has Farty Pants" and "It's a Jersey Thing". They save South Park from New Jersey.
New Jersey is invading every town in the USA and will likely spread throughout the world if not stopped. Randy Marsh and Jimbo Kern send a video tape to Al-Qaeda showing the debauched way of life these Jersey-ites, hoping they would come to help with the war in South Park. The Al Qaeda army arrives at the end when it seemed New Jersey would win and using commercial airline jets, bombs, and various other battle techniques save the town and free the people restoring peace once more.
Al-Qaeda typically wear the clothing style of the Arab, which consists of robes, turbans, and beards.