Edit in JSFiddle

//http://www.jermywells.com

$.fn.greenify = function() {
    this
    .css( "background-color", "green" )
    .css('color', 'white');
    return this;
}

$(document).ready(function(){
    $('#myGreenifiedDiv').greenify();
});

<div id="myGreenifiedDiv">greenified</div>

#myGreenifiedDiv{
    width:150px;
    height:150px;
    text-align:center;
}