I'm not sure that I completely understand. What you're asking is how to get around your parents opposition and wear skinny jeans? Like to school?
Well, what you can do (What I've done before with mini skirts) is wear a pair of jeans or pants that your parents find "acceptable" to school, but have your skinny jeans with you in a track bag or book bag. Once you get into school, go to the restroom and you can change into your skinny jeans. And just before your bus comes at the end of the day, you can change back. But you have to keep in mind that there are still risks to this, and you're parents can find out. You have to be willing to accept what you've done if you are confronted about it.
Or you want to know how to convince your parents that skinny jeans are acceptable? Well, you can't make your parents think anything. You can't control their opinion, but you can attempt to influence it. You can simply explain to them that these pants are in fact in style, though they may not have been a couple of decades ago. State that you would really like to wear them and give them a shot, and you would appriciate them supporting what you choose to wear and how you choose to express yourself.
My personal opinion on skinny jeans? I love them. I own a few pairs of dark washed ones, and they are fab-u-lous~