Yeow! I got zapped in the chest through an unzipped jersey. I was descending at max HR and I thought I was going to seize up as the poison spread into a 6-inch circle of pain. I scraped the stinger out with a stick I found trailside. I'm not allergic but I think the HR plus the adrenaline rush is what made it so nasty. I can only imagine the added anxiety of getting in the mouth.