As a total diversion from this thread, I'm immune to poison Ivy. I was standing in a big patch of it, wearing shorts, when the A-ho** who had been watching me trudge through it for 20 minutes told me what it was. I thought he must be messing with me, so I actually verified it. I had been touching it with my hands and breaking pieces of it out of my way. No reaction to it at all. Some others on the set, not so lucky...
Me too. I had it once as a kid, and have slogged through it a million times since. Apparently that one time of being affected by it was enough to make me immune.