street cred = credibility in your social group (slang) older term "rep" - reputation (slang) Second-language speakers have great difficulty using slang. It's best to speak standard English and recognize slang when you hear it (at work, at school, in TV shows).

It is slang. It's an abbreviation of "credibility". I've only ever heard it used as part of the phrase "street cred", meaning your reputation on the street.

This is slang. It does mean reputation, but outside of jokes I doubt you will use it. An example might be if someone tells an embarrassing story about you, you might say "Oh, come on! You're ruining my street cred." Though I wouldn't recommend ever using it just because this joke is not that funny in my opinion, and can come across as a bit immature.