Another DIY using a mans shirt - I hope your bf/brother/father/housemate has a lock on his cupboard...
Grab a long mens patterned shirt, the longer the better. Cut off the sleeves to create a basic shirt dress as outlined in another one of my posts here. Then cut off the dress at the bottom, making the front about five inches shorter than the back. You will have a thick strip of fabric left over - trim it so that it is a rectangle and then cut it in half lengthways so that you have two long strips of the same width, sew these together so you have a long strip, hopefully about 5 inches wide or more, this is going to be the little 'skirt'. You can hem one edge of this fabric if you want, but I would probably leave mine to fray (stylish or lazy? you decide). Create some rough pleats in this strip of fabric by running a simple stitch along one edge of the fabric and pulling the cotton tight, pushing the fabric along so the fabric gathers to create light pleats. Make the desired amount of pleats, and then sew the pleated fabric to the bottom of the shirt dress. done!