Do you see this rat, in the picture above? This is the "African crested" or "maned" rat. Do not eat this rat. Its hair is poisonous.
Not naturally! The hair is poisonous (as scientists have recently discovered) because the rat eats the bark of a poisonous tree, the Acokanthera schimperi and then "licks itself to store the resulting poisonous spit in specially adapted hairs," which run down its back. When predators—dogs, for example—try to take a bite of the rat, they have a "terrible experience," according to Jonathan Kingdon of Oxford University, and from then on:
When in the presence of a crested rat, a dog that previously had a run-in with one of the animals quivered in fear and wouldn't approach the innocuous- looking foot-long rat.
Interestingly, the poison used by the rat is the same poison hunters in Africa have used on their weapons "for thousands of years" to kill large prey. If only they knew they could just rub some in their hair!