Adult Group Halloween Costumes. Many costumes are designed to be perfect for the whole family. But when it’s time to leave the kids behind or enjoy a late night out on the town, group costumes take a whole new twist. These are the group looks that let you channel some of that freedom you've been earning all your life. Remember that the. Group Halloween Costumes! The festivities that make up the Halloween holiday; the trick or treating, haunted houses, pumpkin patches, parties and even the dressing up in costumes, are all part of this wonderfully entertaining holiday and always much more fun when celebrated with friends and family.