A Man, His House, and an Extra-Dimensional Monster Named Stan

There was a man who lived in a house,
In this house with the man lived a mouse.

This mouse was a big and brown,
And when the man found him, his screams could be heard from the nearby town.

But, fortunately for the man, it was only a mouse.
A big, brown mouse that lived in his house.

At least, that is what the man thought.
For you see, there was another thing that fought

For control of the house from the man.
An extra-dimensional monster named Stan.

This monster named Stan had a horrible plan
To open a portal in the basement of the house of the man.

From this portal the monster came through
And in its wake, terror did ensue.

Stan made its way up the stairs,
Tentacles extended—to skin, flayers.

It was in the living room that it found the man.
And the house became occupied solely by Stan