Slightly nauseous; that's how you feel shortly after taking the "recommended dosage" of the celebrated Robotussin. The taste of cough medicine is, of course, absolutely awful, and drinking ounces of the shit all at once does nothing to make it more appealing. So you sit and try not to barf, hoping that you can keep it down long enough for the active ingredients to enter your bloodstream.
If you persevere for another quarter to half an hour, you begin to notice that your skin feels kind of funny, especially your scalp. Your eyes start to do funny things, like refusing to stay on one thing for longer than a few seconds . . . .
The fun really begins an hour or so after ingesting the awful fluid. The feedback you get from your body, normally taken for granted, suddenly comes to the forefront of your consciousness. Everything feels so weird, like you are a dwarf, or made of cheap plastic, or some sort of wooden puppet (with freaky synthetic chemical as puppeteer).
I guess that "synthetic" is the best word to describe the Robodose high . . . like your brain itself is turned to Styrofoam, and your tactile sensations are being filtered through a plastic sieve which filters out anything at all normal and instead leaves you feeling like, say, a Star Wars action figure come to life. A Jawa, to be exact. . . .