You have bitter taste receptors... in your lungs. Today on NPR's "Science Friday" show I learned that researchers from the University of Maryland had discovered taste receptors identical to those found in the mouth that are responsible for bitter taste.
What's awesome is that when stimulated these cause the bronchial tubes to loosen (more so than any known drug): in other words, this could lead to a very good treatment for asthma. Brilliant!
You can listen to the podcast of the NPR interview here.