[AngelicaDeAlquezar]

I agree with Ambarina that the most common idea for "chasco" is a disappointment.

--¿Cómo estuvo la obra de teatro? --Fue todo un chasco.
--How was the play? --It was a huge disappointment

The idea of "chasco" as "burla" is clear in the sense of "mockery". Despite the dictionary, I have always heard "chasco" used is a synonym of "chiste" or "broma" that one endures, not something one does to others.
The most common kind of sentence I've heard with this meaning is rather like:

"Me llevé un chasco cuando salí del baño y vi que me había escondido mi ropa."
"I felt mocked when I came out of the bath and saw he had hidden my clothes."


@Lou Ann: The María Moliner is a very serious dictionary (to many specialists, better than the RAE's), and I doubt there is a link to it. As far as I know, it can only be bought as a printed book. And one has to be careful... there are a couple of apocryphal versions of it.