This study purposed to demonstrate that English words used in popular songs perform various functions through linguistic performance called code-switching. The excessive use of English words should be avoided because it may foster the tendency to disregard the Korean language among adolescents. On the other hand, however, we need to examine the background of the rapid increase in the use of English words. Without knowing the background encouraging the use of English words and in the current situation that adolescents are crazy about popular songs using English words, we cannot view the use of English words negatively altogether. For this study, we selected songs included in the top ten in the Internet Melon Monthly Chart (http://www.melon.com) for one year from August 2008 to July 2009. As redundant songs were removed from the 120 songs included in the top ten during the 12 months, 69 songs were left, and among them 49 songs that use English words were sampled for this study. The functions of English words used in popular songs are summarized as follows. First, English exclamatory words play the function of interjection that cheers up and changes the mood. Second, English address terms play the function of expressing intimacy among characters in the songs. Third, rhyme and the repetition of the same phrase play the function of meter. Fourth, the repetition of the same phrase plays the role of emphasizing meanings. Fifth, the repetition of synonyms plays the function of harmonizing text structure. Lastly, English words containing suggestive expressions play the function of expressing free sexual desire with passing censorship. Through these uses of English words, the new generation tries to expose their identity distinguished from the old generations and to feel the freedom of deviation as a reaction to daily things. Furthermore, they may satisfy their desire for newness through unfamiliar English words, and enjoy the freedom of expression by expressing suggestive contents in English.