just because you don't like something somebody does in public, doesn't mean the world will stop doing it. Rats, it was absolutely wrong of you to get a girl in trouble, simply because she clips her fingernails, and you don't like it. if i ever found out that a person got me in trouble for doing something petty, and they also lied about it, i would take them out back, and beat them. at least if i beat a person, then when i get in trouble for it, it will be something i actually did that was actually wrong.
as for things people do in public, i hate to agree with Lentower, but i hate you smokers. i do, but you will eventually die (early and painfully), so really i am not exceptionally bothered.