code: function shake(intensity, duration, axis, onComplete, force) {
           if (this._shake.duration === 0 || force === true) {
             this._shake.intensity = intensity;
             this._shake.duration = duration;
             this._shake.axis = axis || this.AXIS.BOTH;
             this._shake.onComplete = typeof onComplete === "function" ? onComplete : undefined;
           }
         }
docs: shake the camera
  @name shake
  @memberOf me.Camera2d
  @function
  @param {Number} intensity maximum offset that the screen can be moved
  while shaking
  @param {Number} duration expressed in milliseconds
  @param {me.Camera2d.AXIS} [axis=this.AXIS.BOTH] specify on which axis you
  want the shake effect
  @param {Function} [onComplete] callback once shaking effect is over
  @param {Boolean} [force] if true this will override the current effect
  @example
  // shake it baby !
  me.game.viewport.shake(10, 500, me.game.viewport.AXIS.BOTH);