slideup 이 반짝거립니다.

<div class="in_1200" id="up">
        <div class="sub_bg"></div>
        <nav class="main_nav">
              <ul>
                <li class="menu">
                    <div class="big_menu">info</div>
                    <ul class="sub">
                            <li class="sub_menu">1</li>
                            <li class="sub_menu">2</li>
                            <li class="sub_menu">3</li>
                            <li class="sub_menu">4</li>
                            <li class="sub_menu">5</li>
                        </ul>
                </li>
                
                <li class="menu">
                    <div class="big_menu">product</div>
                    <ul class="sub">
                            <li class="sub_menu">a</li>
                            <li class="sub_menu">b</li>
                        </ul>
                </li>
        </ul>
        </nav>
 </div>

<script>
//메인네비 드롭다운  

var wid = $(window).width();    
        $('#up').hover(function () {
            if(wid > 1200){
                $('.sub, .sub_bg').stop(true,false).slideDown(500);
            };
        }, function () {
            $('.sub, .sub_bg').stop(true, false).slideUp(500);
        });
</script>