My friend have a black sheep dog

Definitely don't take it if your afraid of it. That would be the worst thing you could do. Why would you even want it if your afraid of it?

If you're scared of it please refuse your friend. You can't be a responsible owner of that dog if you're scared of it. Conquer your fear first and you can be a good pet owner. I say this because if you fear the dog you won't be capable of training it. Dogs can sense fear inside you even if you act that you're not. You won't gain respect from them as a leader of the pact and they won't obey you no matter what if you have this fear inside you. So if you can't conquer that fear, don't accept the dog.

If you are afraid of the dog, you should not take it. You can not be a good pet owner if you are afraid of the perspective pet. The best thing you should do in this case is politely decline your friends offer to give you the dog.