Man that wasn't there - Poem from Identity Movie

I really like poetry in general, and make it a point to collect random poetry that I appreciate, especially from movies. Now I know that this poem is not originally from Identity, but I remember it from there.

Man that wasn't there, Poem in Identity

So, to be clear, the real poem is called "Antigonish" which is slightly longer. But first, here is the one in the movie:

Yesterday upon the stair
I saw a man who wasn't there.
He wasn't there again today.
I wish the man would go away.

Such an eerie poem. It's something like a paraprosdokian. For anyone not familiar, it's pretty much a figure of speech where end ending changes the meaning of the whole thing. So the man wasn't there, then he wasn't there again, but then I wish he would go away... so he was there? Argh. It's annoying me.

Okay, here's the real poem.

Antigonish, by Hughes Mernes

Yesterday, upon the stair,
I met a man who wasn't there
He wasn't there again today
I wish, I wish he'd go away...

When I came home last night at three
The man was waiting there for me
But when I looked around the hall
I couldn't see him there at all!
Go away, go away, don't you come back any more!
Go away, go away, and please don't slam the door... (slam!)

Last night I saw upon the stair
A little man who wasn't there
He wasn't there again today
Oh, how I wish he'd go away...