$(document).ready(function(){  
 
//When mouse rolls over  
$("#mainnav li").mouseover(function(){  
 $(this).stop().animate({height:'100px'},{queue:false, duration:600, easing: 'easeOutBounce'})  
 });  

//When mouse is removed  
  $("#mainnav li").mouseout(function(){  
 $(this).stop().animate({height:'22px'},{queue:false, duration:600, easing: 'easeOutBounce'})  
 });  
  
});