You could have looked in Show unread posts since last visit.
I don't really know how that works. Just clicked it and there is 10 pages of stuff. Skimmed page 1 and 10 and don't see the ct groupon thread. I don't read every DDF post.
Before I posted I typed "CT shirt" in the search box - The most recent thread was this one so I posted it quickly. It should have worked but like I said the search function is not working well.