1. Madonna
You can easily put on any of your black skirt, either maxi, mini, everything works, or pants. Pair it up with your black bandeau, and your rolled up blazer. Make sure to put on your gold jewelry, style your hair just like the Material Girl, and rock the iconic red lips.
2. Gwen Stefani
White bandeau, white skirt OR plaid oversized pants, oversized plaid shirt, white suspenders, plus additional hat or maybe a little beret to add a little kick to the costume. Style your hair like Gwen's, and wear your chunkiest boots OR heels to make the whole look like Hollaback Girl's.