Edit in JSFiddle

$(document).ready(function () {
        $(".thisDiv").hover(function () {
            $(".thisDiv").addClass(function (index) {
                if (index == 0) {
                    return "Green";
                }
                if (index == 1) {
                    return "Yellow";
                }
                if (index == 2) {
                    return "Aqua";
                }
                else {
                    return false;
                }
            });
        });
        $("#reset").click(function () {
            location.reload();
        });
    });
<html>
        <head>
        <title>addClass</title>
        </head>
        <body>
        <table>
        <tr>
        <td>
        <span class="thisDiv">Hover Me 1</span>
        </td>
        <td>
        <span class="thisDiv">Hover Me 2</span>
        </td>
        <td>
        <span class="thisDiv">Hover Me 3</span>
        </td>
        </tr>
        </table>
            <input type="button" id="reset" Value="Reset" />
        </body>
        </html>
 .thisDiv
        {
        background-color:Red;
        width:200px;
        height:200px;
        display:block;
        }
        .Green
        {
        background-color:Green!important;
        }
        .Yellow
        {
        background-color:Yellow!important;
        }
        .Aqua 
        {
        background-color:aqua!important;
        }