what is this trick ??

i learned this the other day and dont have the foogiest idea wat the hell it is and im curious lol plz help


<img src="http://ll.broadbandsports.com/images/22518_bmx_Movie_0001.wmv.jpg" alt="what is this trick ??" title="what is this trick ??" width="150" height="90" alt="what is this trick ??"/>