El Puig, a small town in Spain north of Valencia, celebrates the San Pedro Nolasco fiesta each year on the last Sunday in January. They celebrate the festival in full-swing, with food, music, dancing, and hurling dead rats at each other.

The Batalla de Ratas or ‘Battle of the Rats’ is a centuries-old tradition in the village that has continued to this day. The tradition goes that if someone throws a dead rat at you, you must pick it up and throw it back at your attacker. The rats are supposedly “humanely” killed and frozen days before the festival, and thawed so festival-goers can take turns throwing them at each other.

The cruel tradition started when cucanas (pinatas), which are filled with nuts and fruits and hung all over town as part of the celebrations, started to attract rats. The rats would often crawl inside the cucanas to nibble on the food and so when the locals beat the cucanas, the rats would also be killed and drop to the ground. One year, some of the locals started to pick up the dead rats and hurl them at each other, and thus the tradition was established.

Though animal welfare groups like Partido Animalista Contra el Maltrato Animal en España (PACMA) have tried to fight the “disgusting tradition”, even getting it banned in 2012 on the grounds of animal welfare, the locals have been resolute in sticking to their tradition.

A local told the Wall Street Journal, “In El Puig, they say you aren’t a man until you pick up a rat during San Pedro Nolasco’s fiesta and heave it with all your might.”