A fun idea for the Halloween Party Adult category is to add bottle labels to the bottles you serve.
You can make your own on your home computer printer, using self-stick labels. Think of some creative names like "beetle juice", "witches brew", "essence of yak", your imagination can come up with as many as you need for different varieties of beverages you'll be serving.
If you don't want to make your own, then you can purchase some already made from 4funparties.com or from other online retailers.
Your guests are sure to get a kick out of enjoying cocktails, wines or other "spirits" by a different name!