It's not my term.
It's a sociological term, first coined by Stanley Cohen in the 1970s to describe a disproportionate social response to a perceived problem.
Yep. Cohen´s example was Mods and Rockers, but there have been many subsequent studies on other instances. My favorite book on the subject is Eric Goode's The Social Construction of Deviance. Phillip Jenkins has written on the specific issue of paedophilia as moral panic here:
http://www.amazon.com/Moral-Panic-Changing-Concepts-Molester/dp/0300073879
The strange thing is, no matter how much the phenomena is analysed, there are always enough idiots to support the next one. I guess the world will never run short of suckers.