Via Tai Wiki Widbee
Presumably related to the Rocket Festival:
...a merit-making ceremony traditionally practiced by ethnic Lao people throughout much of northeast Thailand and Laos, in numerous villages and municipalities near the beginning of the rainy season. Celebrations typically include preliminary music and dance performances, competitive processions of floats, dancers and musicians on the second day, and culminating on the third day in competitive firings of home-made rockets...
Coming immediately prior to the planting season, the festivals offer an excellent chance to make merry before the hard work begins.