It sounds like the plot of a Troma flick, but yes, your lungs contain taste receptors. When these receptors encounter bitter compounds, they open up your airways — this discovery could radically improve the treatment of lung conditions like asthma.
Taste receptors are clustered on the tongue as taste buds, but in the lungs the receptors are located on the smooth muscle of the bronchus. You may not be able to taste with these receptors, but they react to bitter compounds like quinine and saccharin. Dr. Stephen B. Liggett and his team at the University of Maryland School of Medicine in Baltimore found these receptors by accident — his team realized that when these bitter compounds interacted with the calcium in the lungs' muscle cells, human airways opened much wider. Says Liggett:
I initially thought the bitter-taste receptors in the lungs would prompt a 'fight or flight' response to a noxious inhalant, causing chest tightness and coughing so you would leave the toxic environment, but that's not what we found [...] It turns out that the bitter compounds worked the opposite way from what we thought [...] They all opened the airway more profoundly than any known drug that we have for treatment of asthma or chronic obstructive pulmonary disease (COPD).
Drinking a lot of tonic water won't cure your asthma — Liggett notes that these compounds will likely have to be introduced to the lungs in an aerosol form to activate these receptors.