Willie bounce is a Jamaican dancehall move, popular in the dancehalls. Click here to see a video from the Dancehall artist, Elephant Man, demonstrating the Willie bounce and another popular move, the Wacky Dip.
Click here for more detail about the constantly changing and increasingly wide varieties of dancehall moves.
Dancehall is an international phenomenon, one of the many Jamaican dance/music forms that as gone global - see here for one example of a Kenyan dancehall artist.
To learn much more about the history and present day forms of dancehall, see this website from Professor Sonjah Stanley-Niaah, of University of the West Indies.