Bought at London's Altars of Death 2011 (Cerebral Bore/Amputated/etc.). I really enjoyed Morphosis' set (despite technical difficulties) and eventually managed to track down their merch guy, who disappeared again straight after selling me a CD-and-shirt combo for £5. Now, that's value.
Morphosis are a death metal band from Ireland who released three demos in the early 90s, then reformed and released a great album in 2009 which I've been listening to quite a bit. This is also one of my favourite shirts. Not quite sure why.