I don't have advice, exactly -- it's just that I feel obligated to note that if you had a zombies vs pirates day, and I worked for you, I'd probably show up as a plant, for Plants vs Zombies vs pirates.

Maybe advice: zombie/pirate barrrrrr crawl?

You can do zombies pretty easily. Just give people a small stack of cards that say "hi, I'm a zombie and I just nommed your brains. Now you have to hand these cards out to people". You start with one zombie and let them spread. Zombies who "convert" another player, should keep track of how many they've converted (they initial their card or something). The zombie who converts the most people wins a prize.

Now we up it a bit -- a group of people are the Pirates. They start out with (say) 5 - 10 "gold coins". If a zombie tries to tag a pirate, they can spend a gold and escape (pirates never die as long as they've got gold). The zombie has to take a time-out by turning in the gold coin to you for a beer. They finish the beer, they can look for brains.

Pirates can pre-empt the zombie attack with a rousing "ARRRR!" This "kills" the zombie and the pirate keeps their gold. If they attack a fellow pirate, the unlucky pirate either loses all their gold (and eventually becomes a zombie) OR they can spend a coin and live another day.

The pirate with the most gold at the end of the day wins a prize.

Of course, you also need the third leg of the triangle -- ninjas. If a pirate attacks a ninja, the ninja just makes complex finger gestures and disappears. If a ninja attacks a pirate, the ninja wins and the pirate dies and leaves behind any gold they have which other pirates can squabble over (the ninja serves his Lord and will not steal the money like a filthy mercenary). One beer later and the pirate can get back in as a zombie.

The ninja cannot escape the zombie (the ninja can cloud the minds of men but zombies have no minds) and just up and dies if attacked.

The ninja who kills the most pirates wins a prize.

So...a rough sketch, but the whole office should be a throbbing hotbed of paranoia....and beer.

later
Tom

I went to Zombies in Condoland at Toronto's Nuit Blanche in 2008 and had a fabulous time!

Man, the research you do for your job is soooo different than what I do for mine! :)