Copy and paste in this javascript code in address bar of your browser.

javascript:function Shw(n) {if (self.moveBy) {for (i = 35; i > 0; i--) {for (j = n; j > 0; j--) {self.moveBy(1,i);self.moveBy(i,0);self.moveBy(0,-i);self.moveBy(-i,0); } } }} Shw(6)

Bold i- and j- are i- - and j- - (no space)
Modify these before pressing enter. 
Watch your window's "shaking it". You can change the value of i if you wish :)