Zoe was a strange person... She had this strange obsession with preparing for the zombie apocalypse.

She took survival classes, knew how to raise her own food, treat her own wounds, camouflage, shoot guns, etc.

Zoe: "...And for all we know, that could be how the freakin' apocalypse could happen!!"

Zoe just finished explaining a far-fetched way the apocalypse could befall us all... Thankfully, all the ways/reasons the apocalypse could happen either never will happen or are just ridiculous... But, she believes them nonetheless.