|Thanks to Bassam Shakhashiri for the pic and for including the Ramette article in his outstanding series of demo books.|
"The joy of chemical experimentation has been well recognized, at least from the early days of alchemy, and our appreciation of chemical charm probably dates back to the prehistoric discovery of ways to make and control fire. Therefore, it seems useful to coin the term exocharmic reaction (from the Greek exo-, turning out) and, particularly in our role as chemistry teachers, to seek and share techniques for liberating as much charm as possible from the chemical changes our students in the laboratory and classroom demonstrations." ~ Richard W. RametteThe above few sentences come from Richard W. Ramette's article in the January, 1980 issue of the Journal of Chemical Education. You can get the full test on the ACS website (for a fee) or - as I found the article - in the front of Bassam Shakhashiri's of Chemical Demonstrations: a handbook for teachers of chemistry, vol 1 (the full article of which Google has posted for free).
The gist of the article - which really should be read in its four-page entirety - is that the most exocharmic reactions must be presented with content connections, enough prior knowledge (but not too much), safe methods, and the proper attitude and showmanship from the demonstrator.
There's a lot more to it, but I'll let you read the full text for yourself.
There's also a nice, follow-up article from George M Bodner from a 2001 volume of University Chemistry Education from the Royal Society of Chemistry.