An individual who uses electronic cigarettes with no mood altering enhancements (nicotine, caffeine, taurine, thc, etc) and who's right to do so is protected by law from FDA or other governmental interference, as their consumable product contains no intoxicants.
Straight - Free from extraneous matter (straight whiskey)
Go Straight - To live a law-abiding life, no longer engage in crime.
Play it Straight - To do something without jokes, tricks, subterfuge, distortions, or the like.
Vaper - Electronic cigarette user. From the word vapor, which is what the user inhales in place of traditional cigarette smoke.
Coined in 2011
I've smoke free since 2/2010, when I became a Vaper
... And I've been nicotine free since 12/2011, when I became a Straight Vaper.