Thanks for the question. I've been offered drugs from kids older than me, maybe as old as 22, but not older than that. It is always hard when it is someone who is older because you feel more pressured to do what they say, but you have to remember to stick to your guns and be strong.
When offered drugs, there are various responses I use like, "No, I'm not into that stuff," or just an easy "No thanks," does it. I've learned that the less you say and move on to the next subject the quicker it gets them off your back. If they ever persist to pressure me, I'll be more forward and tell them "Seriously drop it, I don't want any. "
In all the times I've been asked, people usually handle a decline pretty well; there are a lot of people who don't want to try drugs, no matter what some may think. If they ever kid around or tease you for saying no -- which I have also experienced -- just shrug it off and know you did the right thing. Just walk away. I hope this helps.