Soma, an ancient healing elixir, is theoretically distilled through the urine of reindeer who consume the mushroom. The urine is then fed to the mice, canaries, and house-flies also part of the grand scheme (that part might be animal cruelty). Apparently part of the artistic ambiguity is trying to figure out who's high--do the reindeer know they're high? Do the mice know they're high? Do the mice know that you think they're high? Are the mice freaking out because their parents are coming home any minute and might smell something and last time they got caught their dad said that he was going to send them to boarding school?
Beyond the quasi-scientific trappings, though, the exhibit makes for a surreal set of images. Reindeer strewn about the hall, giant jars of urine, the double mushroom clock. It's an exciting way to spend an afternoon. And kid friendly too! (maybe don't tell them about the pee-pee). Also, if you've got $1000 lying around, you can spend the night in a canopy bed in the middle of the museum and pretend you're Ben Stiller (no guarantees that the giant Warhol paintings come to life, though).
The aforementioned reindeer piss.