Popsugar Entertainment Halloween Mary-Kate and Ashley Olsen Halloween Costumes 14 Mary-Kate and Ashley Costume Ideas That Are Double the Trouble For Halloween October 28, 2017 by Kelsie Gibson View On One Page Photo 8 of 15 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 8 Mary-Kate and Ashley, You're Invited to Mary-Kate & Ashley's Sleepover Party What to wear: Go with plaid pajamas and carry a soft pillow. A bowl of popcorn is optional. How to act: Ask people if they want to come to your sleepover and then start singing about pizza. If you need any inspiration, watch this video. Previous Next Start Slideshow HalloweenAshley OlsenMary-Kate OlsenNostalgiaHalloween CostumesPop Culture Halloween CostumesMoviesHalloween Costumes For Women