if statement not working

Remove the brackets around this in the variable val declaration.

Also, if you're using Firefox, it doesn't recognize innerText so you have to use textContent.

So the val declaration should look like:

// val equals this.innerText (if used) or this.textContent (if used instead)
var val = this.innerText || this.textContent;

You are also going to have to remove, move below the if statement, comment out, or change (see below) the following:

$content.children().fadeOut(400, function(){
    $content.html("");
});

$content doesn't exist and if you are using it as a jQuery variable you have put brackets around it, i.e. $(content).

However, if you are trying to fade out the content of #nav then you can have the statement look like this:

$(this).parent().children().fadeOut(400);

Furthermore, you should try, when possible, to declare variables at the beginning of the function.

So for this to work as you intended you would have:

$("#nav a").each(function(){
    $(this).click(function(event) {
        event.preventDefault();
        var val = this.innerText || this.textContent;
        var HTML = "<ul>"; // you don't really need this
        $(this).parent().children().fadeOut(400);
        console.log( val);
        if (val == "Jannik") {
            console.log("lol");
        }

    });
});