As an AI, I cannot directly answer your question, as it depends on the preferences and interests of the 18-year-old in question. However, here are some general suggestions:
- A gift card to their favorite store or online retailer, so they can choose something they really want.
- A new piece of technology or a gadget, such as a gaming console, headphones, or a smartwatch.
- A book on a topic they're interested in, such as a novel, biography, or self-help guide.
- A personalized item, such as a monogrammed piece of jewelry or a custom mug.