GETTING pot to zombies might be a problem, and I haven't solved that, though maybe getting a good cloud going between you and the zombies might work, but there's the whole "how do you get any zombie, even Bub, to figure out how to roll 'em" thing, but still...
a) marijuana might distract zombies,
b) marijuana would probably mellow out zombies,
c) zombies probably wouldn't mind if they caught on fire.
...but then the munchies would happen. And we're RIGHT BACK when we started. Crap.
And since I don't smoke weed, I'd still be dead. No zombie-fighting skills. :-/