preventDefault() on an <a> tag

Set the href attribute as href="javascript:;"

<ul class="product-info">
  <li>
   <a href="javascript:;">YOU CLICK THIS TO SHOW/HIDE</a>
  <div class="toggle">
    <p>CONTENT TO SHOW/HIDE</p>
  </div>
 </li>
</ul>

Try something like:

$('div.toggle').hide();
$('ul.product-info li a').click(function(event) {
    event.preventDefault();
    $(this).next('div').slideToggle(200);
});

Here is the page about that in the jQuery documentation

It's suggested that you do not use return false, as 3 things occur as a result:

1. event.preventDefault();
2. event.stopPropagation();
3. Stops callback execution and returns immediately when called.

So in this type of situation, you should really only use event.preventDefault();

Archive of article - jQuery Events: Stop (Mis)Using Return False