While this seems like a harmless prank, it is actually quite dangerous.
See, the problem here is that in the case of a real zombie apocalypse, people will ignore the signs warning of impending doom thanks to these not-so-merry pranksters. Also, the chance of Nazi zombies somehow crossing the ocean and menacing Texas is quite low. (Link via DAV,who I'd link to if he had updated within the last 3 months)
Instead, more people should check out this game, The Last Stand 2. To best of a Flash game's ability, it simulates the endless zombie hordes and the skills needed to defeat them. We're trying to get a 10 hour in-service training credit to play this at work, but we're having a hard time of it.
Your Prepared leader.