How do I stop being treated like a child?

I (15M) have a group of guy friends (15-18M, I was 14 when we became friends) who I used to be closer to than the guys in my grade. About 2 months ago we were all hanging out and they were doing drugs. They offered me some and I told them that I was too young and if I got caught I would be grounded for months. Their response was "are you sure? you sound scared" and "don't be such a baby" I said no repeatedly and they called me a pussy for not trying it. They've been calling me a pussy/child/baby ever since. I've asked them to stop multiple times but they just laugh it off. (Note: I have no issue with people doing drugs, I just don't feel comfortable if I were to get in trouble) I've been trying to distance myself from them but I'm not sure what to do to stop them from treating me like a baby/pussy. I just want them to treat me as an equal. What's the best way to approach this situation?