Problem happens on IE8RC1 as well. As of 1.3, a

.trigger("click")

bubbles. The page is doing this:

foo.click(function() {
   var span = foo.find('.goo');
   span.trigger("click");
});

In 1.3, the

span.trigger("click")

will bubble up to the foo element and re-execute the click handler, causing another trigger of the span, etc. If you want the foo.click handler to only execute on a foo click rather than a bubbled child event, add an e parameter and

if (e.target!=this) return;

to the top of the handler. Give this a try and I'll leave the ticket open for now.

I think the proposed answer should address the problem so I'll close the ticket.