http://www.urbandictionary.com/
When you dont understand a word, when it's an acronym or whenever, this dictionary is fabulous. It's is not a common dictionary, its and odd one. It's a dictionary of urban slang, it's not formal it is completely informal, the dictionary give you the definiton of a word or an acronym that it's usually used oraly.
I'm used to go there, due to I usually find words in english, strange ones that I don't know when I'm playing. Moreover, this dictionary could help people that want to learn the urban english, I noticed is mostly used in America. It has been until I get used to it one of the web pages that are on my favourite list of webs.
I think most of the urban slang is there, to the most common to the most strange I ever saw. For example: asap, as soon as possible; afaik, as far as I know; imo, In my opinion... there are tones of this kind of words.
So check it out, I hope it'll be useful for you
