a lap dance on the back. Someone sits down while another person attempts to give a lap dance to the back region.

It was orignally invented by Talia at Candace's 15th birthday party as a truth or dare joke.
After being created the backdance has formed spin offs such as the hardcore backdance and a song by the myspace band "The Weiner Dogs".
"Backdancing" is very popular in NOrthern california.