Psychedelicraft Mod adds drugs into minecraft. You can farm them, buy them, and consume them. It uses shaders, so you can guess the effects are actually worth something. Beware, though: It may make you feel dizzy

It also adds one or two new overlays. You can disable them in the properties file, if you want to.

Psychedelicraft Mod How to install:
Download and install Minecraft Forge.
Download the mod and IvToolkit.
Go to appdata.
Go to .minecraft/mods folder.
Drag and drop the downloaded jar (zip) files into it.
If one does not exist you can create one.
Enjoy the mod.

Disclaimer:
NOT AN OFFICIAL MINECRAFT PRODUCT. NOT APPROVED BY OR ASSOCIATED WITH MOJANG.
In accordance with http://account.mojang.com/documents/brand_guidelines