var banner = new Array();

banner.push('https://i.servimg.com/u/f68/14/08/25/99/angel_14.gif');
banner.push('https://i.servimg.com/u/f68/14/08/25/99/angel_14.gif');
banner.push('https://i.servimg.com/u/f68/14/08/25/99/angel_14.gif');

document.getElementById('pun-logo').firstChild.src= banner[Math.floor(Math.random()*banner.length)];

setInterval("document.getElementById('pun-logo').firstChild.src= banner[Math.floor(Math.random()*banner.length)];",3000);