Here are a bunch of designs that I think would work. The Zombie ones are or might be sold out... but check em out anyway:

http://www.threadless.com/product/141/Corporate_Zombie
http://www.threadless.com/product/632/In_Case_Of_Zombies
http://www.threadless.com/product/757/The_Optical_Illusion_Kid
http://www.threadless.com/product/1161/Death_s_Sweet_Seduction
http://www.threadless.com/product/1145/Yeti_Hated_His_Size_5_Feet
http://www.threadless.com/product/1098/Meashirt
http://www.threadless.com/product/1115/Two_Man_Enter_One_Man_Leave
http://www.threadless.com/product/1064/Ad_Noctum
http://www.threadless.com/product/1063/Yes_You_Are
http://www.threadless.com/product/926/Moral_Of_The_Story
http://www.threadless.com/product/1188/Homage_To_The_Hunter