Bartender: Sir. You cant smoke in here.
Me: Madam this is my inhaler. I have deficient nicotinic acetylcholine and neuromuscular receptors.
This harmless substance containing nothing but a pharmacological suspension and C10H14N2 in liquid alkaloid form relieves the discomfort for a time.
In fact this same substance has been known to improve or prevent; the development of Kaposi's sarcoma, breast cancer among women, preeclampsia, and atopic disorders such as allergic asthma.
Its further been known as an acute antipsychotic. Perhaps youd like to try some?
(All of the above is medically true)
Or if Im too lazy to do the techno-babble I tend toward:
Waitress: Sir, why are you chewing on your pen?
Me: I needed something to get the taste of this food out of my mouth.
I am going to have to find my college professor from two semesters ago and hand him my e-cig for a few days to try it out. I could so see him explaining the chemical composition of the e-liquid to a waitress like that, and correcting her with every minute detail he can muster!!!