Quite possibly my only real contribution to the world's happiness...

gistfile1.php

function humpday(){
  if ((!$_COOKIE['cameled']) && (strftime("%A",time()) == "Wednesday")){
    return '
    <script type="text/javascript">
    var date = new Date();
date.setTime(date.getTime() + (600000));
var expires = "; expires=" + date.toGMTString();
document.cookie = "cameled=yes" + expires + "; path=/";
</script>
<iframe width="560" height="315" src="//www.youtube.com/embed/Vs5QJi-dX-4?autoplay=1" frameborder="0" allowfullscreen></iframe>';
  }
}