JQuery Ajax Post to C#

I'm trying to retrieve JSON Object on C# here is my JavasSciprt post but I'm unable to hande it on codebehind, thanks!

$.ajax({
    type: "POST",
    url: "facebook/addfriends.aspx",
    data: { "data": response.data },
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function (msg) {
        location = '/facebook/login?URL=' + ReturnURL + '&UID=' + response.authResponse.userID + '&TK=' + response.authResponse.accessToken + '';
    }
});

I've tried to retrieve data like:

Request.Form["data"]
Request["data"]