I dont think I will vape in front of them, too much to explain.
I have no kids, so thus far it's not been an issue. I just do it in the corner. If spied I plan on saying that smoking is so addictive when you start young that as an adult one must pretend to smoke to stop smoking.
Among my friends who never smoked, the most common lesson taught that had the desired affect was, "I tried smoking, worst decision I ever made." Unfortunately the best reenforcement seems to be "try this" which results in the response "gag gag, people do this?!?!".