Edit in JSFiddle

<html>
<head>
    <!-- Prebid Config Section START -->
    <!-- Make sure this is inserted before your GPT tag -->
    <script>
        var PREBID_TIMEOUT = 700,
            OUTBID_TIMEOUT = 700;

        var adUnits = [{
            code: 'div-gpt-ad-1460505748561-0',
            mediaTypes: {
                banner: {
                    sizes: [[300, 250], [300,600]]
                }
            },
            bids: [{
                bidder: 'appnexus',
                params: {
                    placementId: '10433394'
                }
            }]
        },{
            code: 'div-gpt-ad-1460505661639-0',
            mediaTypes: {
                banner: {
                    sizes: [[728, 90], [970, 90]]
                }
            },
            bids: [{
                bidder: 'appnexus',
                params: {
                    placementId: '10433394'
                }
            }]
        }];

        var pbjs = pbjs || {};
        pbjs.que = pbjs.que || [];

    </script>
    <!-- Prebid Config Section END -->
    <!-- Outbid Integration Start -->
    <script>
    (function (w, d, o, f, k, c, a, m) {
    w['OutbidTagObject'] = k;
    w[k] = w[k] || function () {
    (w[k].q = w[k].q || []).push(arguments)
    }, w[k].l = 1 * new Date(),
    w[k].cmd = w[k].cmd || [],
    w[k].config = w[k].config || {};
    if (c) w[k].config.ch = c;
    a = d.createElement(o),
    m = d.getElementsByTagName(o)[0];
    a.async = 1;
    a.src = f;
    m.parentNode.insertBefore(a, m);
    })(window, document, 'script', '//www.outbid.io/static/banners/v1.3/outbidtag.js.php?ch=www.twizl.com', 'outbidtag');
    outbidtag = window[window['OutbidTagObject'] || 'outbidtag'];
    </script>

    <!-- Outbid Integration END -->

    <!-- Prebid Boilerplate Section START. No Need to Edit. -->
    <script type="text/javascript" src="//acdn.adnxs.com/prebid/not-for-prod/1/prebid.js" async></script>
    <script>
        var googletag = googletag || {};
        googletag.cmd = googletag.cmd || [];
        googletag.cmd.push(function() {
            googletag.pubads().disableInitialLoad();
        });

        pbjs.que.push(function() {
            pbjs.addAdUnits(adUnits);
            pbjs.requestBids({
                bidsBackHandler: sendAdserverRequest
            });
        });

        var f = function () {
            if (!pbjs.adserverRequestSent) {
                setTimeout(f, 100);
                return;
            }
            <!-- Outbid Integration Start -->
            if (typeof outbidtag.setAutoTargeting === 'function') {
                outbidtag.setAutoTargeting();
            }
            <!-- Outbid Integration End -->
            pbjs.que.push(function() {
                pbjs.setTargetingForGPTAsync();
                googletag.pubads().refresh();
            });
            f = function () {};
        };

        function sendAdserverRequest() {
            if (pbjs.adserverRequestSent) return;
            pbjs.adserverRequestSent = true;
            googletag.cmd.push(function() {
                <!-- Outbid Integration Start -->
                outbidtag(function () {
                    f();
                });
                <!-- Outbid Integration End -->
            });
        }

        setTimeout(function() {
            sendAdserverRequest();
        }, PREBID_TIMEOUT);

        setTimeout(function() {
            f();
        }, OUTBID_TIMEOUT);


    </script>
    <!-- Prebid Boilerplate Section END -->

    <script>
        (function () {
            var gads = document.createElement('script');
            gads.async = true;
            gads.type = 'text/javascript';
            var useSSL = 'https:' == document.location.protocol;
            gads.src = (useSSL ? 'https:' : 'http:') +
                '//www.googletagservices.com/tag/js/gpt.js';
            var node = document.getElementsByTagName('script')[0];
            node.parentNode.insertBefore(gads, node);
        })();
    </script>

    <script>
        googletag.cmd.push(function () {
               googletag.defineSlot('/1038998/twizl300x250atf', [300, 250], 'div-gpt-ad-1460505748561-0').addService(googletag.pubads());

            googletag.defineSlot('/1038998/twizl728x90hp', [728, 90], 'div-gpt-ad-1460505661639-0').addService(googletag.pubads());

            googletag.pubads().enableSingleRequest();
            googletag.enableServices();
        });
    </script>
</head>

<body>
<h2>Prebid.js with Outbid Integration</h2>
<h5>Div-1</h5>
<div id='div-gpt-ad-1460505748561-0'>
    <script type='text/javascript'>
        googletag.cmd.push(function() { googletag.display('div-gpt-ad-1460505748561-0'); });
    </script>
</div>

<h5>Div-2</h5>
<div id='div-gpt-ad-1460505661639-0'>
    <script type='text/javascript'>
        googletag.cmd.push(function() { googletag.display('div-gpt-ad-1460505661639-0'); });
    </script>
</div>

</body>
</html>