The purpose of this study was to investigate the usage of slang and aggressive language expression in teenagers` spoken language. The analysis results were summarized as follows: Of the entire subjects, 95% were using slang. Most of teenagers were using slang. Middle and high school students showed a higher percentage of slang usage than elementary school students with no gender differences. As for the characteristics of the slang vocabulary list, such slang as ``좆나, 씨발, 새끼, and 개-`` recorded a high frequency by the school levels and gender. There were differences in slang vocabulary between elementary school students and middle and high school students. As they moved to middle and high school, their usage of sex-related slang increased. Even though there were differences in frequency between boys and girls, the gap in the form of slang used between them narrowed. Of the entire subjects, 81% were using an aggressive language expression. "Curses" recorded the highest frequency by the school levels and gender, being followed by "belittlement/slander," "threat" and "imprecation" in the order. As for the characteristics of aggressive language expression according to the subtypes, person curses including ``미친년, 미친놈, 씹새끼, 개새끼, 멍청이, 바보, 병신, and 새끼`` and non-person curses including ``지랄, 지랄하다, and 좆같이`` showed an even distribution in the area of curses. A phenomenon of using curses in opposite to the gender of the other was also observed. They used such metaphorical expressions as ``얼굴을 갈아주다, 뒷동산으로 갈래?`` in the area of threats and usually belittled the actions and appearances of the other in the area of slander. Imprecation was in very low frequency, containing content of wishing death upon the other or taking his or her possessions.