DaF; Deutsch als Zweitsprache; German as a second language; DaZ; German as a foreign language ; Questionnaire (method.) ; Opinion poll ; Cross-cultural pragmatics; Pragmatics, cross-cultural; Pragmatik, interkulturelle; Intercultural communication ; Jugendliche (Sprachverhalten) ; Adolescents (language behavior) ; Jargon; Youth language ; Sprachattitüde; Linguizismus; Linguicism; Prestige; Monolinguale Ideologie; Monolingual ideology; Sprachliche Unsicherheit; Linguistic insecurity ; Multilingualism; Polylingualism; Plurilingualism ; German