I will not be told! Its up to me after all!

So ladies, gents all of you who have a relationship with your work colleagues!! So we as in my colleagues and I are going out in Friday after work and today the organiser announces that firstly I have to dress up? Why I ask? What's wrong with how I normally dress on a Friday? Well you have to dress  up to the place she says and in fact you have to dress up in 1930's style! Well I'm not doing that i bellowed, I mean I already dress rather nicely and I'm not willing to come to work dressed like that besides I don't actually have anything, her response? Wear some pearls! Hmm if only it were that simple then my other colleague waded in with his size 9 boots- look he goes some people can't dress up- very funny what's he trying to say that I dress like a tramp?! Anyhow does this make me a part pooper? I don't quite understand the need to conform at this level of society- I have enough of that in my personal background in particularly in light of how we like to be uniform at weddings and other milestone events! So a Friday night work outing is off limits in its attempt to dictate how I dress or behave!