Ahh, reverse psychology. Turns out it's not just for toddlers anymore. Although this video is in Spanish, what happens is pretty clear: a man pretends his Dachshund's medicine is actually a delicious, forbidden treat. He holds the treat near his chest and tells his dog "No!" whenever the dog looks interested.
Needless to say, the dog takes the bait and gobbles up the medicine like it's bacon sent from doggy heaven. The only downside? This method will only work if you have the type of dog to ignore your "No"s. I guess that's the (one) upside of having a stubborn dog?