There are tons of scientists conducting research on how to cure the diseases of the world. All we need is one who
Anyway, once the zombie virus has infected everyone and we're all vulnerable and mindless the aliens will swoop down and attack us, thus creating the alien apocalypse.
However, if the aliens eat our brains they will become zombie aliens and if they can't defeat our mass zombie army and some escape without knowing that they are infected they could go out into space and create an Inter-galactic zombie alien apocalypse.
Yeah. I know. Crazy. And by crazy I'm talking about my brain and the unsettling thoughts that live there. I feel bad for whatever zombie eats it.
Oh and the boys finally decided against renting a movie and watched TV instead.