How can I get my mom to let me watch R-rated movies?

I want to watch Bad Teacher and Saw The Final Chapter and the Hangover
1 and 2 and other things! But my mom says I can't watch R-rated
movies. But I've seen Saw 3! I'm 12 years old and my birthday is
February 10. I'm close to being thirteen. A teenager!! And most of my
friends can watch R-rated movies!!! I know lots of inapropriate things
like... nevermind. I think I'm capable of watching R-rated movies.
Innapropriate or scary. I'm not a baby. I just don't understand!!!!!
Please give me advice! I want to watch these movies! Plus, we own a
movie store! (no joke) I mean, seriously!! We own a movie store and I
can't even watch R-rated movies!!!!! UGH. I just don't get my mom!