I've had the opportunity, and will probably want to try weed just once some day, but as of yet I have never taken up the offer. I'm worried about the fact that I don't really know what I might be taking. I might be affected badly by the drugs and not have a good experience, I might have a good one and things could get out of hand. With alcohol it is very easy for me to control myself as I know my limits and have never felt out of control, but I have no idea what would happen if I took drugs.
Furthermore, the people I know who do take drugs/ who usually have them at parties aren't my closest friends, I wouldn't feel comfortable trying drugs for the first time with them.