Also known as Aughney's Law. Whenever you purchase a blinging* new top to wear on your birthday, you will invariably pack in haste due to being hungover/hungry/late/stupid/all of the above, and leave it behind you in Dublin. You will then be forced to wear out an old top you have had for ages, and will be cross all night (all right, not all night. Just until you're drunk enough not to care).
FRIENDS: Are you wearing that out?
FRIENDS: Didn't you wear something similar before-
FRIENDS: Like your last birthday?
YOU: Certainly not!
FRIENDS: Yes you did- see, here is a picture of you last March in the exact same top.
YOU: Bugger off.
MOTHER: What are you wearing?
YOU: Yes. What's wrong with it?
MOTHER: Nothing. Black is very slimming.
Conclusion: Friends think you a cheap, fashionless ho. Mother thinks you are fat.
*I'm sorry. I hardly ever use rapper slang. In my defence, it is gold and shiny so there really is no other way to describe it.