-All you Zombies- was not about zombie invasion

When I heard the title of this Heinlein short story, I initially thought it would be about some zombie invasion taking place with main character repeating "all you zombies" as that person makes way through a horde of the brain eating undead with the help of a shotgun. Later I heard that  it was about time travel with grandfather paradox when the movie Predestination (2014) was released.

What I wasn't expecting a story as strange as this, and without spoiling much I will say go read it as soon as possible. After my experience with Stranger in a Strange Land, The Moon is a harsh mistress and Starship troopers, I can say for sure that Heinlein coming up with something like this didn't surprise me and found it very amusing.