var banners = new Array(); 
banners[0] = '<a href="http://ads.betsafe.com/redirect.aspx?pid=7569&bid=1286" target="_blank">100 PLN Za Darmo w w BetSafe! To Nie Ściema!</a>';
banners[1] = '<a href="http://record.affiliatelounge.com/_n7kP3Xu3_AxoofBpZ-qTpmNd7ZgqdRLk/1" target="_blank">Bonus 111zł na dobry początek! Obstawiaj w Betsson!</a>';


index = Math.floor(Math.random() * banners.length);
document.write(banners[index]);