function nah(){
  document.getElementById("goplay").innerHTML = '<iframe style="border: 1px solid white;width:150px;height:250px;" scrolling="no" src="http://goplay.cz/prpg/150x250.php"></iframe>'; 
} 
setInterval("nah()", 10000); 

function prvy(){
  document.getElementById("goplay").innerHTML = '<iframe style="border: 1px solid white;width:150px;height:250px;" scrolling="no" src="http://goplay.cz/prpg/150x250.php"></iframe>';
}    
setTimeout("prvy()", 0);