From a young age, we have practised saying "Danger! snake" and "Danger! don't touch" when looking at story books with snake pictures...and reinforcing with messages like what would you do if you see a snake in the garden...move away and come and tell a grown up, we don't touch snakes etc. The "Danger!" (said with drama, like an exclamation) word is a handy concept because you can then apply to other situations, like electrical cords and running onto roads, when you need to get their attention fast.