One man had five blades through his face and another walked the streets of Phuket with the wide, blunt handle of a hammer through his.
These men are apparently mutilating their bodies to purify themselves – and to "take on the sins of the community".
But more specifically, they are apparently committing these torturous acts (without anaesthetic) to celebrate going vegetarian.
"It's a little more more extreme than just switching from pork to tofu," says Amy Poulton of Wayfairer Travel.
"Phuket's vegetarian festival traditions include macabre scenes of ritualised mutilation, impaling, cutting, partial skinning and bloodletting."
The participants are expected to obey these ten rules:
An unofficial 11th rule states participants should wear white throughout the festival, perhaps to embolden the flowing red.
Although it is sold as a vegetarian festival, the food sold during the nine days is strictly vegan.
Everyone taking part completely abstains from meat, poultry, seafood and dairy products.
They also ditch "pungent vegetables" including onion and garlic, regarded as "heating" and contributory to aggression and lust.
The motivation behind this abstinence is an attempt to reach good health and calm peace of mind.
Every stall taking part is marked with a yellow flag with red Tahi or Chinese signs.