Because you did not post any HTML so I guess '.pull-me' is an 'a' element.
Pls try below code(remove .click()):
$(document).ready(function() {
$('.pull-me').click(function() {
$('.panel').slideToggle('slow');
});
$('a').toggle(function() {
$(this).html("Click to close!");},
function() { $(this).html("Click to open!");
}); // modified here
});
You are triggering click event when the page first load.