jquery turn preventdefault on and off

Question

Here's what I tried so far:

var preventDefaultFunc = function(e){   
            e.preventDefault();
        }

then I call it in the click function later:

$('.item').click(function(e){

            var $this = $(this);
            var $thisChild = $this.find('.item-content');
            if ( $this.hasClass('big') ) {
                return false;
            }

            $this.on(preventDefaultFunc);
    // make the box bigger and load the article inside it here
});

I did it this way so I can turn it off again later, because the div in question needs to allow clicks within it once it's made big.

The on/off switch isn't working, since it's supposed to stop the page from loading the link within the box, so that I can make the box bigger and load the article with ajax instead. Note that on/off is the jquery 1.7 version of bind/unbind.

Any suggestions?