Question

<script type="text/javascript">
$(function(){
    $(".user_ava").click(function() {
        $("div:.userMenu",this ).animate({
            height: ["toggle", "swing"],
            opacity: "toggle"
        }, 200, "linear");
    });
});
</script>

Error: message ( Uncaught Error: Syntax error, unrecognized expression: :.userMenu )

Answer 1

The colon in "div:.userMenu" is incorrect, jquery does not recognize it.
if you want to select all <div> with userMenu class the syntax is

$("div.userMenu",this );

Full script:

<script type="text/javascript">
$(function(){
    $(".user_ava").click(function() {
        $("div.userMenu",this ).animate({ // you had a colon here for some reason
            height: ["toggle", "swing"],
            opacity: "toggle"
        }, 200, "linear");
    });
});
</script>