A grayanotoxin is a naturally occurring toxin produced by plants from the family Ericaceae which, periodically, finds its way into honey via nectar from rhododendrons. This honey can, in rare cases, cause death in humans and other animals. Yet the risk of poisoning has not stopped many peoples throughout history from harvesting this honey and intentionally ingesting it for its hallucinogenic and intoxicating effects.
Well, obviously (retroactively) inspired by Episode 43 of Ask the Meadmaker, a documentary was produced several years ago about a tribe in Nepal which risks life and limb to collect this psychotropic honey in Himalayan Mountains. It's a fascinating little piece.
Check it out, then make sure to swing by the Meadery to see an alternative technique for making honey intoxicating. Warning: Video not suitable for acrophobes.