The one good thing about Australia is that there's a plant that grows in NSW called the gympie-gympie. Anyway, this plant looks completely innocuous and bland even, until you have the misfortune of touching it, in which the fuzz on the leaves will sting you with thousands of microscopic needles filled with horrifying pain poison, which will continue to act for several months because the poison also has stabilizing compounds.
Anyway I often think about what a wonderful bioweapon that is, just carefully grab a leaf and make tea out of it, then give it to someone you hate.