IDIOM - an expression in the usage of a language rhar is peculiar ro itself either grammatically or in having a meaning that cannot be derived from the conjoined meanings of its elements.
In other words, it's American Slang which you may not always get. In fact, idioms can make you totally lost in conversations! We Americans seem to roll them off our tongues very easily and we are so busy gabbing that we really are clueless when we even use them!
All the animals are in a panic. The elephant's sneeze would blow the monkeys out of the trees, the feathers off the birds, the stripes off the zebra. Even the fish and the fly, the crocodile and the kangaroo, know what a catastrophe that sneeze would be. "Please don't sneeze!" they beg. . . .