Here's a couple of fun things a friend of mine at another board showed me.
Put the following into your web address URL bar and watch the fun:
javascript:x=0;e=document.body;e.style.position="absolute";function rt(){e.style.top=100-(50*Math.cos(x*Math.PI/180))+"px";e.style.left=100+(50*Math.sin(x*Math.PI/180))+"px";x+=5}; setInterval("rt()",50);void(0);
Also try this one:
javascript:R=0; x1=.1; y1=.05; x2=.25; y2=.24; x3=1.6; y3=.24; x4=300; y4=200; x5=300; y5=200; DI=document.getElementsByTagName(%22img%22); DIL=DI.length; function A(){for(i=0; i-DIL; i++){DIS=DI[ i ].style; DIS.position='absolute'; DIS.left=(Math.sin(R*x1+i*x2+x3)*x4+x5)+%22px%22; DIS.top=(Math.cos(R*y1+i*y2+y3)*y4+y5)+%22px%22}R++}setInterval('A()',5); void(0)
Note: Please make sure you have the latest Java updates before putting them in.
Note 2: To fix this, just hit the Back button, and you'll be fine.