I can't remember how the discussion started in
#mongers, but links were
pasted and I followed them and ended up reading “Fly
Agaric, Father Christmas and Lunch with a Toxicologist”.
There's an account of a common Siberian shamanistic ritual where the shaman would dress in a ritual costume looking very much like the classic Father Christmas costume, eat fly-agaric (Amanita muscaria) and walk into the woods and urinate in the snow. The reindeer would eat the yellow snow and get intoxicated too. One of the common effects of fly-agaric is a sense of flying…
Lots of other interesting stuff in that article, you ought to read it.