BTW: If you ever see someone TYPING AN ENTIRE SENTENCE IN ALL CAPITAL LETTERS that means SHOUTING!
It is not proper netiquette to TYPE IN ALL CAPS (even in email), in fact, it's annoying.
The majority of the expressions you see above are not acronyms, but rather shorthand used while text messaging or IMing.
There are several terms to describe different kinds of jargon including anacronym, backronym, weather acronyms, city acronyms, leetspeak and textonyms.
Online enthusiasts are learning that shorthand are in fact called acronyms, but this is incorrect.The difference between acronyms and shorthand is that with acronyms, (for example, 'ESP' is an initialism for 'extra sensory perception' whereas 'esp. The online practice is to refer to shorthand, initialisms, or abbreviations as acronyms.