I love this shirt.  Flashes me back to wipe after wipe against Ragnaros.  Of course, now you can almost solo this stuff (in fact, I used to solo Onyxia level 60 for a quick 100 gold each week) and every jackass has a Hand of Rag, so it doesn't have the impact it once had.  Vanilla content was much cooler than the current stuff, although I kind of like ICC.  

If you've never had to come up with a 40 man raid to kill something, this shirt means nothing to you.