Blarg is a unique word, being the only word that not only means anything you want it to, or is used to show disinterest or boredom, but also is the only word that thousands upon thousands of people have claimed to have made up but has been around since man discovered they could use tools. Hobo Dave and Raymond Donn are amongst those who claim to have created the word, as well as some wierd dude called John who worked in the Games Workshop in Falkirk. I have also been known to use the word frequently in the past. I suppose, the true use of this word is to fill a gap in a sentence where appropriate. If a stoned person says "blarg", it is usually used to replace a word they cannot think of, or which they have forgotten.
"Blarg yer maw!!"
"Blarg tae aw da yids and swankers! (Hobo dave)"