I wanted to put, "slang," but I'm taking a test, so I played it safe.
I think the slang term for "slang" is mu'mey ghoQ "fresh words", not mu'mey chu' "new words".
The phrase mu'mey ghoQ fresh words, slang in TKD isn't said to be slang itself. Note also the antonym, mu'mey Doy' tired words, words used by older Klingons that are eschewed by the younger ones.
Thank you both.