Across industries, generations and income levels, the buzzword is "contagious." In communications we have to seed our clients' communications with that term. Otherwise, the publics they address will assume they are just not in-touch.
Part of this phenomenon stems from the contagiousness of memes of Facebook, which is used by more than a billion humans on planet earth. New research involving 100 million people found that feelings expressed on Facebook are contagious. The most contagious are the positive ones. And there are plenty of those on Facebook. Here is coverage of that research in The Wall Street Journal (sub. req.)
An amazing recent ebook "Contagious Content" explains why Facebook's law of attraction is tilted toward the positive. The authors are Brian Carter and Marketo. Here you can download it, no charge.
In copywriting for a new client, the only real criticism on the first draft was that I didn't explicitly use the term "contagious" enough. It was not enough, at least for them, to imply that force field operating.