jquery adding random class without repeat

I'm using a function on my website to randomly addClass to a div. works fine, but I can't find a way to not repeat the same class twice one after the other (cause sometimes the same class is added and we can think the code is not working)...

here is my jquery code :

$("#switch").click(function(){

var classes = ["vert", "escalier","reverse","demi_escalier","demi_escalier_2","ligne" ];

$("#logo").removeClass().addClass(classes[~~(Math.random()*classes.length)]);

});

can anybody help me with this ?

thanks