It's really difficult to answer. I often face to this problem when I watch movies in English, you know american slang and there are hundreds of different phrases and words and also in Russian we use slang. I think at first you should learn better formal Russian and then plunge into slang. Check out some useful words which are usually used by young people облом - fail прикол - joke, something funny замутить - to start a relationship задрот - nerd

Канать - быть подходящим Космос - выражение восхищения чем-либо Мыльница - плёночный компактный фотоаппарат Баян - повторно опубликованная информация/шутка Дичь - что-то странное

Список фразеологизмов (идиом) русского языка https://ru.wiktionary.org/wiki/%D0%9F%D1%80%D0%B8%D0%BB%D0%BE%D0%B6%D0%B5%D0%BD%D0%B8%D0%B5:%D0%A1%D0%BF%D0%B8%D1%81%D0%BE%D0%BA_%D1%84%D1%80%D0%B0%D0%B7%D0%B5%D0%BE%D0%BB%D0%BE%D0%B3%D0%B8%D0%B7%D0%BC%D0%BE%D0%B2_%D1%80%D1%83%D1%81%D1%81%D0%BA%D0%BE%D0%B3%D0%BE_%D1%8F%D0%B7%D1%8B%D0%BA%D0%B0

ты ставишь меня в тупик. - for example, asking a question for which we don't have an simple answer, and we don't know how we can answer it correctly. Or you did something, and what we don't know how to react. so we will say "ты ставишь меня в тупик".

I think you could come up with informal words and phrases you personally use in your native language and then ask italki users here to translate them. Btw, we borrow a lot of informal phrases from english. Only today i saw an article with the word 'факап' (fuckup) in it used by a businessman. 'Эпик фейл' (epic fail) is also quite popular.