Oh wow I thought it would be ok to just cut the green bit off (although thinking about of course the whole potato would have the 'greening' chemical :-\ ). Thats only if a little corner close to the skin is green, i would chuck a potato if it was green through the middle though, although i do that because it tastes icky

TBH though I didn't actually know it was POISONOUS, I thought green was just not great, like eating green bananas or tomatoes.