Sagging pants is illegal in some states of the US and offenders can be sent to prison.

Read this article from the New York times : "Are your jeans sagging? Go directly to jail!"
http://www.nytimes.com/learning/teachers/featured_articles/20070831friday.html

And see the lesson plan, including a debate with each students in a different role
http://www.nytimes.com/learning/teachers/lessons/20070831friday.html

Visit also those two links recommended in the lesson plan:
- a history of hip-hop style : baggy pants, jump suits and overall
http://www.pbs.org/newshour/infocus/fashion/hiphop.html
- an outline of the debate about indecency
http://www.pbs.org/newshour/extra/features/jan-june04/indecency_3-31.pdf

Ellen Foucher launched the thread on e-teach with she discovered this news article about the law against sagging pants passed by a mayor in Louisiana:
http://blog.washingtonpost.com/offbeat/2007/06/louisiana_mayor_bans_sagging_p.html

Then Sylvie Brod found several resources for all levels, about this protest from a Florida preacher offended by this style :
- for intermediates (around A2), this short piece of new, complete with the video and the transcript
http://www.wtlv.com/news/local/news-article.aspx?storyid=79317
- for advanced (B1 upwards), this very ironical article from the Washington Post with vocabulary of different styles ( I discovered "commandos")
 http://blog.washingtonpost.com/offbeat/2007/04/florida_preacher_fights_hip_ho.html