Here are some possible crossword clues that fit the theme:
Straightforward:
* Valley Girl slang (2 words)
* "Like, totally" is an example (3 words)
* California dialect (2 words)
More playful:
* She's "totally" into him (3 words)
* "Gag me with a spoon" is a phrase (4 words)
* "Valley Speak" (2 words)
Tricky:
* A language spoken in a valley (2 words) (This one is meant to be misleading - it's not a real language)
The best clue for your crossword will depend on the difficulty level and the other clues in your puzzle.