How to animate objects on screen on certain events

Question

I want to make the clown dance when he catches a hat (I have a tween for that) who otherwise will be simply standing, Basically I need to animate objects on certain events and then stop, I see so many game makers doing that, I know nothing about it, tried a lot on my own but with no success

Answer 1

a simple sample:
you can download it here: http://www.flashdersi.com/flash/diger/adobeforum/hittest.fla
import flash.events.Event;
addEventListener(Event.ENTER_FRAME,fCheck);
var bMove:Boolean = false;
function fCheck(evt:Event)
if (! bMove)
  if (mcHandClown.hitTestObject(mcHat))
   bMove = true;
   mcClown.gotoAndPlay(2);
if(mcClown.currentFrame==1)
  bMove = false;
mcHat.startDrag(true);