Need help to understand some urban slangs I was watching "America's Best Dance Crew" and the judges always say something like "it's really dope", "this is sick" etc. What's meaning of "dope/sick" here? seems like they're some sort of urban slangs. Any help will be appreciated.

Introduction: about me My English name is Raien, I made it up myself, and didn't even know what it means, just thought it'd be a quite unique name. I was born and raised in Shanghai, CN, which is becoming a very large modern city, also is getting more and more crowded. There're people everywhere. I graduated from college about 2 years ago, and since then I have been working for a software company which is a vendor for Microsoft, and that is why my job requires skills in English. I love pop music, movies, basketball, internet stuff and so on. and I do have interest in different cultures. I'd like to meet people all over the world, cuz I always think earth is just like a big family. We have such short lives, and we should not spend our lives on wars/fights/hates, we should love each other, don't you agree? Anyway, I found this cool site and was hoping I could meet cool friends and also great language partners. Good luck to all of you! :)