Cacher is the code snippet organizer for pro developers

li {
	display: block;
	cursor: pointer;
	color: #000;
	padding: 0 0 8px;
	overflow: hidden;
}

.sub-menu {
	display: none;
}

$('.parent-title').click(function(){
    $(this).toggleClass('active');
    $(this).next('.sub-menu').slideToggle();
});

<ul class="menu">
    <li class="parent-title">
        Parent
    </li>

    <ul class="sub-menu">
        <li class="child-title">
            Child
        </li>
    </ul>
</ul>