We use such words and phrases in no official situation, with friends.

For example: офигеть[ofigi`et`]-to go crazy

мне пофиг[mnie` po`fig]- I don’t care

зашибúсь [zashibi`s]  - cool, excellent

You can find a lot of slang and idioms here http://ochenporusski.com/russian-slang-vocabulary/

There are a lot of slang words which used in professional spheres (computer slang,military slang and etc).

Yeah, there definitely is Russian slang. I have a book on it which has more than 100 pages and I can confirm that most of the words in there are used. Generally speaking, most slang expressions exist - as in other languages - to describe everyday situations (be it eating, drinking, working...), but also topics that one would not openly discuss (mainly things that one would normally do in a bathroom or in a bedroom).

There are also several levels of slang. While there are slang expressions that anyone can say without being looked at, there are others which one should not use actively if one wants to avoid that people think something bad about oneself. There is also this thing that when foreigners use slang, it sounds weird, at least to some native speakers.

For example, Lilia told you about the word "pipets". This is a more socially acceptable version of "pisdets". The latter one, you may have guessed, has to do with going to the toilet, but it is used the same way as Lilia described for "pipets". Another example: When you are positively shocked or amazed by something, you can also say "nichego sebe", or, if you want a level below that, "nihuya sebe". This last one has to do with a certain part of the body, referred to as "huy" in Russian slang. I strongly advise not to use any phrase that includes the word "huy". In English, you have a similar phenomenon: Think of words like "shoot", "dang", "darn" and so on.

As for certain social groups, I can confirm that there are slang expressions that are only used by people that belong to a certain group.

I can give you student slang)

хвост - an exam that you've failed and have to repeat

столовка - a canteen in a  university

курилка - a place where students usually  smoke

прогулять - to play truant

курсач - a writing project

влом - reluctance

физра - physical education

забить - decide not to do smth

There is Russian slang that spoken among teenagers:

hello! - здарОва! 

how are you? как делИшки?

thanks спасИбки, пасИб, спс

and there is one common word пипЕц which you can use when you are shocked, amazed.

    Sorry dor being out of topic , i'm interested in learning Russian so I'm looking for partners interested in learning English , I can be online for an hour aday ,and i think it might be helpfull if we make discussions on skype and yet it would be so entertaining , looking forward to hear from you guys , until then , good luck