window.addEvent('domready', function() {
    var dob = document.id('ctl00_mainContent_UserDateOfBirth');
    if (dob == null) return;
    var dobFormat = 'MM/DD/YYYY';

    dob.addEvent('focus', function() {
        if (this.get('value') == dobFormat) {
            this.set('value', '');
        }
    });

    dob.addEvent('blur', function() {
        if (this.get('value') == dobFormat || this.get('value') == '') {
            this.set('value', dobFormat);
        }
    });

});