We each have one, but few admit it.

I once had an imaginary friend.
His name was Unitard.
He was cute and pink and evil.
Unitard liked to blow things up.
A few of his favorite things to asplode were:
Fuzzy kittens,
Baby chickens,
And pre-schools on weekdays.
One day Unitard got tired of the usual explosions.
He decided to try something new.
So he strapped on his pack of explosives and
Bounced,
Bounced,
Bounced,
To the nearest carnival.
Nobody noticed him.
Nobody notices imaginary friends.
(That's why most of them grow up to be serial killers.)
Unitard bounced up onto the merry-go-round.
Fiddled with sticks of dynamite,
Wires,
Buttons,
Wires,
Buttons,
More sticks of dynamite.
He bounced off of the merry-go-round just as it began to move.
Bounced,
Bounced,
Bounced,
A safe distance away.
He watched as the little children on the merry-go-round waved to their parents.
He watched as they rode
Around,
Around,
Around,
Up and down, and up and down, the little horses and unicorns went.
Unitard couldn't wait any longer.
He paused a slight moment for the obligatory evil cackle.
Then he pushed the Red Button.
Horses,
Unicorns,
Children,
Went flying.
Fling.
Fling.
Fling.
Those children mostly survived
(With only slight major concussions, things of that sort).
The old ladies that the horses' poles stuck into upon landing,
Those ladies mostly did the opposite of 'survived'.
Later on, the Merry-Go-Round Explosion was under investigation.
They say they found my fingerprints in all those investigatable spots,
And that I am their prime suspect.
How they found my fingerprints in such places
On something that exploded so magnificently,
I will never know.
But I will be thinking of my ex-imaginary friend, Unitard,
And he will undoubtedly be thinking of me,
Pausing to direct the obligatory evil cackle in my direction
While I sit there in my jail cell
With my new imaginary friend, Jarvis.