Is this normal?

Boys!

It's nice that they're learning to play together, but ...

Playing in the backyard:
Inventor to Painter: Mr. Repairman, I need to fix my car.
Painter to Inventor: I'm the car breaker. I'm breaking your car.
I to P: NOOoo. I need to fix my car.
P to I: I'm going to break your car.

Playing in the living room:
Painter, while lying on top of Inventor: Here's a nice soft carpet.
I gets up.
P: Come back here carpet.
I, lying on top of P: Here's a nice soft carpet.
P gets up.
I: Come back here carpet.
This scene is from today. Yesterday it was lying on "nice soft grass" outside. The day before it was stepping on "the stairs".

Playing anywhere:
One of them: I'm shooting my bomb-shooter at you.
The other: I exploded your bomb shooter. I'm shooting poison at you.
The first: I ran away from your poison. I pushed the "die" button.

Or this:
First: I threw you in the trash.
Second: I threw you in the diaper pail.
First: You're kitty poop.
Second: You're a poopy diaper.

Et cetera, et cetera, et cetera.

Help! I'm living in a house of lunatics and they're trying to turn me into one.

Or maybe I already am crazy and this is all normal.