Phase???

When we got Goblin he was 4 months old.And sometimes when he stays in the house to long something happens its weird he becomes mean and jumps and attacks could it be a phase??? Please please help if your dogs gone threw this!!!

This is NOT a phase and has the potential to become a very serious problem. Goblin is being very dominant and must be taught not to behave in this way - ever!
As soo as he starts to jump up at you avoid eye contact and do not speak to him at all. Get the whole family to deal with him in the same way. As he prepares to jump up at you raise your knee fast until it is at right angles to your body - do not turn away from him as this encourages the behaviour - if you are walking around, carry on. When he tries to jump again, raise your knee, fast, again. This will give you some space and show him that he is not gaining your attention from his actions. Beware that this behaviour will get worse before it gets better - the dog is thinking ,"It always got me attention before so I'll try harder and it will work again!" Do not give in! Totally ignore him until stops jumping. The trick is as soon as there is a lull in the jumping you must be ready with a very firm,"Sit!" Then give a calm pet and a very calm,"Good boy."
I would suggest you always leave a short line on him in situations when this happens - if he doesn't respond to the sit command you then have some control method without touching him.
Also if he starts to try to bite you, use the line and give him a really good correction - this is no time to play at it - say "No! Sit!" again if he refuses correct him with the line.
I hope this is helpful and if you think the correction bit is a bit over the top just imagine how you will feel with a fully grown dog jumping and biting you! It is not a situation I would want!
Good luck - let us know your progress.

Looking waaaay back...Cody did the same thing esp; when he wanted HIS way. I had little scars on my arms to prove it!!! Of course Carrie is right (what else?) With the help of a wonderful trainer, who used Carrie's technique, I got right to the problem because it was getting unbearable, uncomfortable, nasty and frightening! And as I said before, I knew NOTHING being a first time dog owner so I was very very consistent with eliminating this problem. I finally took control! Cody is by no means perfect after 9 yrs but he does NOT jump (constant reinforcement) DARE to mouth me in any way. This had to be one of the worse problems I had to deal with!!!! Good luck! It takes time and patience!!!

Is this a male trait? I have a 12 year old female sheltie. I've owned her for 3 years. My folks owned a female from about 2 years till she passed on at nearly 20 y/o. My sister owns a female which they bought as a pup and she is nearly 4. I don't remember this trait in either of my family's dogs and of course didn't have my lovely lady when she was that young. I would love to have another sheltie some day and am wondering if this aggression is a trait of a male or if it has been seen in females of the breed as well.

This is not a trait of breed or gender. This is a dominant dog controlling a situation by it's behaviour. As with any dominant behaviour the aggression will stop once the dog is safe and secure in the knowledge that it is not the pack leader.