5mg of awesome Hydrocodone (plus 500mg of the painkiller acetaminophen)
Opiates have a great physical feeling that will make you smile. The problem is that to get the most effect from many of them, you need to crush them up and insufflate (snort) them, inject them in a vein with a syringe, or 'plug' them (liquify them and stick them up your butt).
Luckily, Hydrocodone has a GREAT oral bio-availability, so you can just swallow these pills and have just as nice of a high as you would have had with any of the other methods. Plus you don't have needle marks or something up your butt. And that's (usually) a good thing.