$(document).ready(function() {
                    function showKitten() {
                        $('.kitten').slideDown(500);
                        $('pre').slideUp(500);
                    };
                    
                    $(document).cheatCode({
                        code: 38383940,
                        time: 500,
                        callback: showKitten
                    });
                });
            

Press in quick succession to see a kitten.

Key Code Generator