Why is my brother so anoying?

My brother is 19 nearly 20 he still lives here with my parents and he's such a F***in d**k! He comes in my room for no reason and starts to sing dance mess my room up do anything to anoy me really and then doesn't go out for 30min! Then since he anoys me I go down stairs and get my xbox game (cod7) that he always play's and thinks it's his, so after that comes in my room and search's all of it then see's that it's in my pants! So he starts attacking me! So i give back to him so he will stop! Then for no reason he goes to tell my mum that is smoke weed and she should look on my bed if she doesn't bealive him! Cause i have like pipes and stuff on it! Then i go outside to moe the lawn and he starts to jab me with a stick! My mum doesn't do anything caus she's sick of me always arguing him! I hate him i wish he would just die! PS: My mum now hates me for smoking weed! (He ruined my life!!)