Dextromethorphan HBr. You have to take 500mg+ to really experience it. Extremely easy to get, just use some acting skills at the checkout, and dress like a nerd when buying it. Don't get the cough syrup, get the liquid gels. RESPECT THIS SHIT it will get you EXTREMELY EXTREMELY FUCKED UP. My third favorite drug, behind OxyContin and shrooms.
DXM is jesus. Yesterday when i got home from school, i swallowed 2 bottles of Robitussin Cough and a bottle of Robitussin CoughGels. I remember trying to do the moonwalk on top of my dad's truck. I also rememeber trying to look for the button you have to push every 180 minutes to save the world, but them i remembered that was only on Lost and i went home and tried to think of new and interesting sexual positions for my friend Maria.