What are some good themes/ideas for girls to dress up as for a 23 year old birthday party?

So it’s one of my friends 23rd birthday party next weekend and she loves to dress up (think skanky halloween) whenever there’s a birthday party or some kind of get together. Our last theme was Heaven & Hell and she dressed up like an angel while me & her other friends were devils. What do you think our new sexy, spicey theme should be for her birthday next weekend?