Everything has rules. They are either shoved down your throat or accepted with all one's heart. The thing is, there are rules that are just meant to be broken. No, murder is not one of them. But the lighter things like dressing up (or down, for that matter) should be done or practiced with one's heart's content. Of course, you still want to be respected, but breaking (or bending) some of them is quite liberating..and fun. Try it once in a while and I'm sure you'll get the hang of it. :)
The fashion rule I love to break: When you're on the bigger side, never tuck in your top.