I stayed up late,

Well very, very late

Suddenly there was a sound

"THUD"

Upstairs, that's what I thought.

In my house there are 23 cats

So it was most likely that 

one of them knocked down

something and

that was the cause

But what frightened me more

than the sound itself was

             ⇩

Ok, they were frightened

They may have been very much 

astonished.

 

But your posture actually 

really surprised me, my cats!

Are you really cats?

Or some kind of strange creature 

somehow creeping 

into my house??

They remained like this for a while.

It seems that 

the common knowledge that

cats have a bending back

does not apply to my cats...