Rompers were pretty much made for those sartorially uninspired days. No assembly required, just add shoes!
Skirts and shorts are really easy to style as well. Throw on a slouchy, neutral colored t-shirt (or if you got six hours of sleep instead of four, you probably have enough brain power to go with a print) with some slight tuck-in action and you're good to go. Scarves make an easy throw-it-on-as-you-walk-out-the-door accessory to keep in the arsenal as well.
(photos collected from people, garancedore, and fashiontoast)