Either way you look at it driving at 40 mph and filing your nails, or your nail file grinding at 40 mph, it's just not a very good idea.
As young adults, there is so much expected of us. There are days where you have to multi-task things that really shouldn't be done at the same time; Like filing your nails while driving. I'm a believer in enjoying everything you do and never doing anything simply because you think you "should." But this doesn't apply if you're a slacker. Being lazy is lame.
Leggings are not pants. They are tights that happen to be a solid color. Leggings are called such because they are the shape of your legs. Exactly the shape of your legs. Please wear pants with your long sweater.