Most commonly used in the same context as "oh, damn". Used to express frustration, anxiety, depression, etc. Ocasionally the second syllable is prolonged to demonstrate any emotion in an extreme fashion.
a combination of the words: blah, argh, and ugh
can mean a variety of things including bored, dissatisfied, unhappy, angry...etc...
Internet Conversation:
Person 1: Hey, What's up?
Person 2: Nothing much... Todays a really really boring day!
Person 1: BLERGH
Person 2: Yup. I think that sums it it all up.
Utterance used in answer to questions when one is in the confused mental state experienced immediately after waking, or when too tired or otherwise mentally incapacitated to deal with any complex thought process. Can also be used when simply not understanding a complex question or not knowing an answer to a complex question. Originally intended for IRC or IM use, but can be used vocally.