by critters <1yr old:
Once on the finger, during feeding time, when he swarmed out of his box and I tried to move him BEFORE his mouth was full
Once on the eyebrow [gently], after she drifted out of my hair onto my face when I wasn't paying attention. Hmmm handy tip: eyebrows sort of look like mice when you're a snake!
Both were no big deal - just tiny pin-pricks, which I let bleed out, then disinfected. I don't think I'd like being bitten by my two adult snakes though!