Recently, social networking is becoming more and more common among people from different parts of the world. Nigerian youths especially students in tertiary institution of learning are now seriously engaged in communicating with each other both at the local and international levels through these social networks. They are involved in chatting, conveying comments, remarks or feedback on a particular issue at a given social network such as WhatsApp, Facebook and Twitter. This paper, therefore, examines the negative effects of social networking language on written English of Nigerian undergraduates. The major aim of this paper is to show to which extent the language of social networking affects written English of our Nigerian undergraduates.