I need to allow my readers to get information when they click on a word but
want it to remain totally hidden (except for the word being underlined and/or
a different color) until clicked on. The help file for office does this but
uses a bit of javascript named javascript:AppendPopup. I couldn't find the
actual code for it or any help at all in office help or on the web about how
to do that. But it doesn't have to be javascript, just an effect similar to
what that code does in the help file.

An alternative would be a baloon type popup that activates on a mouseover or
mouse click. The hidden text option is preferred though since it allows
greater user customisation of what is displayed in the document.