it seems christians in iraq have a similar tradition. but in lieu of john the baptist's feast day, they commemorate mass baptisms by Jesus and the apostles.
"Iraq's approximately 180,000 Assyrians and a large number of their Muslim neighbors celebrate the festival, called Nusardil, by splashing, if not dousing, each other with water. Many children and young adults use the occasion to mount high-spirited water wars."
at least it's better than hurling explosives at each other.
(via Katolik Shinja)