$(this).attr("clicked") == "aa"

if ($(this).attr("clicked") == "aa"){
  alert("aa");
 }

<a id='Comedy' hoverb='green' clicked='aa'>want to laugh</a>

$('.left a').live("click", function() {


 if ($(this).attr("clicked") == "aa"){

  $(this).css('background',black);
  alert("aa");

 }

  else {

 //do somethingelse

}

});

<a id='Comedy' hoverb='green' data-clicked='aa'>want to laugh</a>

$('#Comedy').on('click', function(e) {
    e.preventDefault();
    if ($(this).data("clicked") == "aa") {
        alert("aa");
    }
});​

$('#Comedy').on('click', function(e) {
    e.preventDefault();
    if ($(this).attr("clicked") == "aa") {
        alert("aa");
    }
});​

$(this).css('background','black');   <---- black needs to be bound in '' ..Missing that

$(this).css('background',black);

$(this).css('backgrond','black');