They've been going on for years.
They had a mad one a couple of years ago which they held on one of the uninhabited island near San An. They ran out of water after a few hours and had to rely on Vodka to see them through the rest of the night.
Your best bet is trying some of the markets or beaches where the travellers hang out. You won't have much joy in the usual bars/clubs, believe me , I've been trying for years to attend one.