Is there a way to toggle a boolean variable in C#?

You can define an extension method like this:

public static class Helpers
{
    public static bool Toggle(this bool value)
    {
        return !value;
    }
}

So that you can write something more meaningful like locked = locked.Toggle()

Hope it helps

You could also do:

locked ^= true;

Yes. Use the following:

locked = !locked;