What might be the biggest water gun fight in the world is happening in Myanmar and Thailand right now.

This is Bangkok on April 13:

(AFP/Getty Images)

Millions of people across Southeast Asia this week have been engaged in raucous street battles, celebrating the New Year by splashing, spraying and dousing water on friends, family and strangers.

The three-day water festival has several names, depending on the country.

In Thailand and Myanmar, where the water fights are particularly epic, the celebration is called Songkran and Thingyan respectively. What these photos don't show you is how hot it is. So the whole getting doused in water thing is pretty refreshing. Here's three ladies in Chiang Mai in northern Thailand getting in on the action:

(Getty Images)

The water festival actually has its roots in Buddhism. It symbolizes cleansing. Splashing water on someone is a way of showing respect and is supposed to bring good fortune.

Here's a fatherly figure raining some good fortune on a well-prepared motorist, also in Chiang Mai:

(Getty Images)

"The water throwing we see now comes from how water used to cleanse spirits," Dr Thak Chaloemtiarana, a professor of Southeast Asian and Thai Studies at Cornell University in New York, told CNN.

"Originally one would go to temples and pour fragranced water on Buddha images to cleanse them, or you would go to visit your elder relatives and pour water on their hands to ask for their blessings, and it was quite an elegant religious ceremony."

Well, times have changed:

Another street scene in Chiang Mai. (Getty Images)

This was Myanmar's capital yesterday:

(Paula Bronstein/Getty Images)

(Paula Bronstein/Getty Images)

Back in Thailand, these kids know how to fight water with water. He's even got reserve ammo.

(Taylor Weidman/Getty Images)

A drive-by:

(Taylor Weidman/Getty Images)

Classic:

(Taylor Weidman/Getty Images)