Celebrated in the ninth lunar month of the Chinese calendar, the annual festival promotes the abstinence from meat in order to aid in preserving good health and peace of mind for all the participants. 

Although the origins of the festival are unknown, the celebration is famous for various forms of self-mutilation.

The ceremonies invoke the gods over the period of the nine-day celebrations during which the participants are acting as mediums of the gods through the fire-walking, body with various objects through cheeks, arms, face, legs or back, partial skinning; limb slashing with swords, axes and knives or standing near firecrackers as they are lit. Participants who perform ritualized mutilation believe that the Chinese gods will protect them from harm, and little blood or scarring will occur. 

The festival takes place near the six Chinese temples scattered throughout the Phuket town. Members of Chinese-Thai community bring their household gods to the temple, along with offerings of food and drink to benefit from spiritual energy that fills the temple. Source(s) and more information about the festival can be found at [Wikipedia] [Phuket.com] [Official Website]