What could be more festive than spending a night locked in an art gallery with a dozen reindeer and a fridge full of psychedelic drugs? The urine is collected by handlers and stored in fridges by the walls, which also hold both dried and fresh fly agaric mushrooms. By day they're locked, but at night the fridges are opened, allowing people staying over to sample the contents. However, because only half the reindeer are fed the mushrooms, it's impossible to know which bottles, if any, contain hallucinogenic urine.