EventTarget

var $preventAllEvents = $('input');

// The magic code
var oldAddEventListener = EventTarget.prototype.addEventListener;

EventTarget.prototype.addEventListener = function(eventName, eventHandler)
{
  oldAddEventListener.call(this, eventName, function(event) {
    if(!$preventAllEvents.is(':checked'))
      eventHandler(event);
  });
};

function clickHandler (event) {
  $(this).toggleClass('distinctive')
}

$('.level1').on('click', clickHandler);
$('.level2').on('click', clickHandler);
$('.level3').on('click', clickHandler);

// css
div {
  border: 8px solid #8cf;
  padding: 16px;
  margin: 8px;
  text-align: center;
  border-radius: 5px;
  background-color: cornflowerblue;
  cursor: pointer;
}

.level1 {
  width: 300px;
}

.distinctive {
  background-color: hotpink;
}

//html
<div class="level1">Level 1 <span></span>
  <div class="level2">Level 2<span></span>
    <div class="level3">Level 3<span></span>
    </div>
  </div>
</div>

<br/><br/>
<input type="checkbox" id="stop"></input>
<label for="stop">Prevent all events</label>