Heh, I liked using the placebo effect for morning coffee at my office (they had decaf and regular). I didn't really want to acquire a caffeine dependency, so I'd pour a bit of caffeinated coffee into my cup (not a consistent amount), and then fill it the rest of the way with decaf. Then, as I walked back to my desk, I'd think to myself, "Wow, there's a mysterious amount of caffeine in this cup! I might wind up with a lot of energy!"

Worked pretty well.