Dogs Strange Behavior

My Cancer guy friend came over to help move some furniture. My Scorpio dog was behaving strangely. I've never seen him act like this. He's a 3 year old German Shepphard. He was growling, hackles up, tail down, head down, and was standing in front of me the whole time my friend was here. I was afraid he might bite or attack my friend.

My dog has NEVER acted like this before. He is usually very sweet and loving. He is protective of me but never to this degree or behavior.

I've heard it said that if your dog doesn't like someone then they are a threat to you. Anyone have any experiences like this? Explanations?

How do you feel about this guy?

I love him and my dog.

My friend is not a dog person. Heck, he may have even been secretly afraid of my dog. He is intimidating looking, like a huge wolf.

My 9-yr old 3lb teacup chihuahua , born under Sag, usually is on the defense when anyone comes over, however, she tends to warm up to people typically fast and will roll over in a heartbeat thinking someone is going to give her belly rubs...lol! However, when the maintenance guys come around to fix something she is "true to form" with her ankle biting skills....each and every time...lol! She just can't stand them...lol!

Either your friend is a weirdo or he's just upset with new face plus scary noises. Did your friend properly introduce himself or act all on guard the entire time? Makes it hard for dogs to warm up to a stranger when they're giving off vibes like that.