EDIT: It sounds like you want to be able to call this method without any HtmlHelper object at all.
If the method needs an HtmlHelper, you will not be able to call it without one.
You should rewrite the method so that it doesn't need an HtmlHelper.
You can make an overload with fewer parameters:
public static Jquery Extra(this HtmlHelper htmlhelper, string message) {
return htmlHelper.Extra(message, null);
}
In C# 4, you can also use an optional parameter:
public Jquery Extra(this HtmlHelper htmlhelper, string message, IDictionary<string, object> htmlAttributes = null) {
I highly recommend that you also add an overload that takes an anonymous type:
public static Jquery Extra(this HtmlHelper htmlhelper, string message, object htmlAttributes) {
return htmlHelper.Extra(message, null, new RouteValueDictionary(htmlAttributes));
}