Scenario suggestion?

[Criesto]

Okay, so when my friends and I play the game, I'm ALWAYS the zombies. No one else likes doing it. To be honest though, I don't really mind. The only thing I do get kind of frustrated with, is the fact that, my friends don't really try to play the game. They never go for the objectives, so I ultimately win every game. Which, sounds like it would be a good thing for me. But it gets boring, and I like feeling the theme of the game. My friends end up just running around, trying to make their character the most BA thing around, and kill as many zombies as they can. They also like just trying to hole up in a building, fending off the swarm.

So basically, does anyone have a scenario (not one that comes with the game) that they think would fit what these heroes want to do? And preferably something with a little more gusto than "Dies Zombies Die!" This way, the heroes can have what they want, and I can go back to not being frustrated with them.