Today is the start of the water festival in Laos and Thailand. This is a story told in Laos to explain why Lao people pour water on each other on the New Year in the fifth Lunar month. The story is called Nang Sangkaan.
The origin of the parade of Nang Sangkaan is not Buddhist, but Brahmanism. Later, Lao people changed the tradition, but kept the idea of carrying the Buddha images and respected persons in the procession and pouring water on them. This video was made for 2009 Lao New Year, and originally posted here.