My cat is flipping out.

I have a cat who is about 8 months old.. He is not neutured.. Today he started flipping out, his tail got extremely fat, he was hissing at me, meowing very angrily and ready to attack me. He has done it now twice today.. I actually have him locked out of the room right now because right now I don't trust him.. Is this a hormonal thing because he isn't neutured yet?

it is possible that this is the cause. Is there a reason why you havent got him neutered yet?

No, just haven't gotten around to it.. He is in indoor cat, and isn't spraying. This is the first time he has acted like this.

It's because he's not neutered. We went through this with our first male, right after he was neutered he went back to being a sweet cuddly boy.

ya neuter him, I agree with that definately. It is actually better to do before they mature so less chance of cancers and stuff when they are older. Plus, the longer you wait, the more likely he is to begin spraying and once that starts, it is much harder to stop.

he might be smelling an intact male hanging around outside.

It's spring, and there's a very good chance that there is a female in heat somewhere in your area. Cats have a remarkable ability to smell things from long distances. My guess is that he is reacting to a female outside and turning that aggression to you.

Yes, getting him neutered ASAP will help.