Edit in JSFiddle

$(function() {
    $("body").height($(window).height() + 2000);　$(window).scroll(function() {
        if ($(window).scrollTop() >= ($("body").height() - $(window).height())) {$(window).scrollTop(1);
        }
        else if ($(window).scrollTop() == 0) {$(window).scrollTop($("body").height() - $(window).height() - 1);
        }
    });
});

body {
height: 2000px;
background: url("http://kachibito.net/sample/endless-roop/bg01.gif") ;
}