Every generation has its own catchphrases and slang... partly to define themselves against their parents, also to distinguish themselves from other groups. The English language is a very elastic, dynamic communications paradigm. It's always changing, evolving... that's what makes it so fun to use, write with, play with (oh, the so many puns and innuendo!).
The new slang annoys us because we are old and becoming inflexible. We want to correct every misuse of a word, the verbification of common nouns (I'm gonna science this shit up!), the contracting of words and entire phrases. But it's okay. It's cool, even.
What evs, yo? I finna go an 'lax; enjoy the show.