A "druggy" is someone who uses or takes drugs regularly, often in excess. This can also refer to someone's behavior or appearance being influenced by drug use.
When people talk about a friend or acquaintance being a bit of a druggy, they usually mean that this person has a tendency to take too many substances or get high too frequently. It might be because the person is trying to cope with stress, emotions, or problems, but the conversation can also just be about someone who likes to party and have fun, often without worrying about the consequences. You might hear people saying things like "Oh, she's such a druggy" when they mean that this person always seems spaced out or tired after going out at night. The tone of voice is usually casual and not necessarily judgmental.
A drug addict or abuser.
