Billie is the queen of monochromatic ensembles. Case in point: her orange get-up for the 2018 ASCAP Pop Music Awards red carpet. We can't think of a more functional and comfy outfit to wear on Halloween.
What to wear: Knee-length orange gym shorts and an orange t-shirt, with a matching windbreaker overtop. Bonus points if you also have a pair of orange sneakers handy.