A: My skirt.
Do not buy a skirt a size down thinking that it will be okay. It won't be okay. What will happen is you will suck in so much that you will bust an organ and you will internally bleed to death. Or worse, you will show up to a department meeting looking like Peggy Bundy had she followed her dream to be a nine-to-fiver. And then you will bust an organ and die. Doubly so if you buy that tiny skirt in leopard print.
I've had a few emails and comments asking about the time constraints on this 30 for 30 challenge. Guys, guys, guys -- there is no real time limit to this challenge. It's simply putting together 30 outfits out of 30 items. No worries if it happens in 30 days or if it happens in two years. However, if it takes you 2 years to remix 30 items, I might have to disqualify you, meaning you won't get a participation ribbon at the end of the challenge.