$.fn.randompar = function(clas, options) {
    
    var settings = {        
        navId: 'nav'

    }
    if(options) $.extend(settings, options);
    
        
    return this.each( function () {
        
        var me = $(this);
        var size;
        var randomIndex;
  
        
        function init () {
            size = $(clas, me).size();
            randomIndex = Math.floor(Math.random() * size)
        }
  
        function show () {
            var show = $(me).find(clas).get(randomIndex);
            $(show).show();
        }       
        
        function hide() {
            $(me).hide();
        }
        

        init();
        show();
            

    }); 
}