var mess = new Array(
'<img src="images/menuCorp1.jpg" border="0">',
'<img src="images/menuCorp2.jpg" border="0">',
'<img src="images/menuCorp3.jpg" border="0">');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);