Its your mums house. Show some respect. Move out, get a job and then get a dog.

well give whoever reasons why you should get a puppy. Or you can just beg for a puppy.

I believe someone has already asked this, but how old is the dog? That could create a bigger difference in the dogs personality growing up. Taken too soon from the mother and siblings, and the dog could develop behavioral problems that could have been squelched by spending more time learning from it's mother. (I got my kitten at seven weeks, which was far too young, but there was no choice in the matter there, and trust me, he was and IS a pain in the arse!) Secondly, Chihuahuas are known for being high-strung and neurotic, though that's not always the case. Research the breed and be armed for what might come from having a pure bred dog! Knowledge is your best friend, the good and the bad of it. Most importantly, your mom had a bad experience with a dog...do you think you could have her come with you to check the dog out, get to know it, before taking him into your home? It might help if she has time to get to know the personality, because lets face it - a dog CAN be "too much trouble", especially when it's a puppy, and if it's your first dog. Research, research, research dog training, dog behavior, house breaking, the works, to show that you are a responsible pet owner and not just taking this on a whim. And you're 16? She might also be thinking about if you leave for college! She really HAS to be okay with the dog, and willing to adopt the dog as her own if for any reason you can't take care of it anymore. I hope this helps.