I have done acid like 4, 5 times. 2-3 hits each. Shrooms three times, got sick two times, the first time I accidentally turned on deliverance on tv and couldn't figure out how to turn it off. I used DXM god knows how many times, did it via Robitussin and at one point had a shit ton of extract. I did ketamine twice, and then like the 2nd year of college my room mate was getting this Chinese substitute that was twice as strong. DXM, ketamine and other stuff like that is more of a dissociative that can produce hallucinogenic effects. They are actually anesthetics if anything.
DXM was a problem however. Its not addictive, its habit forming and can create dependence. I was using it in a fashion similar to speed, it kept me up at night and it was a rush. No pain, and of course once I took enough I would end up dissociated and would just trip out until I fell asleep. It got worse when I discovered that it can wipe your tolerance to cannabis. Bud also could take a 300mg dose and turn it into a 1200mg dose. It was a rush like heroin.
During that time It began to effect my performance in TF2. I had to be in that same state on DXM as I was when playing before. I had to stop. Now I'm still trying to comeback from that shit, it sucks.
Aside from the bad times, I did candy flip a few times (mdma and acid) and once I jediflipped (2 hits of acid, some mdma and an 8th of shrooms) ive dicked around with lsa and and other little things. Now I just smoke and drink.
Drugs are crazy, be careful.