Trampolining

var trampoline = function(fun){
  var args = Array.prototype.slice.call(arguments,1);
  var result = fun.apply(this, args);
  while(typeof result === 'function') {
    result = result();
  }
  return result;
};

var countDown = function(n){
  if(n === 0){
    alert("Happy new year!");
    return;
  }
  var thunk = function(){return countDown(n-1);};
  return thunk;
};

trampoline(countDown, 5);