Dressing up for work.

Ok, so, I'm not working Christmas Eve.
This means that I will probably be working New Year's eve and Boxing day. My problem with this is that if we work New Years we are expected to dress in fancy dress. I work in a casino, there are a lot of drunk men and a lot of perverts, plus, there's free champaign going around, every one will be even more drunk.
I want an outfit that won't make me look ridiculous but also wont make me look like a huge slag. I've been looking at outfits online but I can't find any kind of in-between. Most of them are just way too revealing for me to feel comfortable, especially when I have to bend over chipping machines and tables, anything too short is going to flash my bum and anything too low cut and my boobs will fall out.
I liked the idea of going in as Harley Quinn but they are too revealing, so is Minnie Mouse. The ones that aren't revealing are all too expensive though.
Can anyone help me come up with ideas?