The Shim Sham, or Shim Sham Shimmy, dates back to Vaudeville performances in the early 1900s. Today it is often performed at the end of a tap dance show with an invitation to all dancers in the audience to come onstage and join in. For more on the history and additional steps of the Shim Sham, see:
http://www.tapdance.org/tap/steps/shimsham.htm
http://www.theatredance.com/tap/
http://swingexpress.com/SwingExpress-fr/video(SE)/shimshamvideo.html
http://www.jitterbuzz.com/less7.html