[1] Heinrich Löffler refers to Jugendsprache as a transitory non-standard language (“Lebensalter-Sprache”: “age-language”)[2] with attention to the time period.
[3] Researchers claim that its main function is achieving separation from adult speech and to signal group solidarity.
Acronyms such as "YOLO" ('You only live once'), have increased in frequency, to condense text messages.
Researcher-curated dictionaries/style guides create an always-dated image of youth language that misses the way young people actually speak, because that youth language evolves too quickly to be reflected in formal research.
Later, ‘astrein’, ‘cool’, ‘nice’ or ‘geil’, often enriched with further emphatic forms (‘oberaffengeil’), emerged.