Acrostics, mesostics and trash metal

If you are still unclear as to what an acrostic is, the first two sentences of the definition given by Wordsmith.org (found here on Answers.com) may help dissipate any remaining ambiguity:

An acrostic is not an angry insect ("a cross tick"), any more than an oxymoron is a big dumb cow. Rather, an acrostic is a poem, in which the first letter of each line spells out a word.

This definition actually debunks two deeply rooted assumptions that I had concerning dictionaries:

• Isn't it unusual for a dictionary to start defining a word by what it does not mean?
• Would you have ever thought it possible to turn to a dictionary for comic relief? I thought humor — if at all present — could only reside in the citations used to illustrate the definition of a word in context.

This may just be that Wordsmith.org is not a conventional dictionary. As refreshing as it may be, this definition could be amended a little. Poems are indeed the preferred embodiment for acrostics, because of their mostly fixed layout, but Arnold Schwarzenegger's letter can be added to a long line of texts in prose which benefit from a two-dimensional reading. Among the more elegant and recent is Linton Weeks's farewell review in the Washington Post.

In both examples, the "hidden" message was meant to be discovered by everyone. A variant of the acrostic and a more effective cryptographic pattern is the mesostic, which also has you look for subtext by reading the text vertically. While acrostics rely on the first letter of each line, mesostics use the middle of each line.

Do you remember how we were supposed to be able to hear the voice of the devil by playing trash metal tracks backwards?