Bring Out Your Undead
None Shall Pass
When I started at ThinkGeek, all there was was swamp. All the merchant monkeys said I was daft to build a t-shirt empire in a swamp, but I built it all the same, just to show 'em. It sank into the swamp. So, I built a second one. That sank into the swamp.
You're pretty safe with this one as long as the dude doesn't argue that he's not dead yet. And for the most part in this scenario, the only thing your dead guy is likely to say is "Braaaaains." And with the Black Knight by your side, bellowing "None Shall PASS!" it's all good. As long as you bring a mop and some duct tape to take care of the knight himself.
Black Knight and cart full of zombies above the words "Bring Out Your Undead" on a black, 100% cotton shirt. As an added bonus, all the green ink on this shirt glows in the dark.