Disclaimer: I own pretty much nothing. I went on J.K.'s website and found this song was n edited scene, but I thought that it deserved its place in the books. I tried to fit this as closely to the book as I could, so anything in italics is Rowling's exact words, taken either from the book, or her website.
"That does look good," said the ghost in the ruff sadly, watching Harry cut up his steak.
"Can't you-?"
"I haven't eaten for nearly four hundred years," said the ghost. "I don't need to, of course, but one does miss it. I don't think I've introduced myself? Sir Nicholas de Mimsy-Porpington at your service. Resident ghost of Gryffindor Tower."
"I know who you are!" said Ron suddenly. "My brother's told me about you—you're Nearly Headless Nick!"
"I would prefer you to call me Sir Nicholas de Mimsy—" the ghost began stiffly, but sandy-haired Seamus Finnigan interrupted.
"Nearly headless? How can you be nearly headless?"
Sir Nicholas looked delighted. The smiles on anyone over first year were suddenly plastered on their face. Nick took up an impressive looking pose, and began to somberly sing.
It was a mistake any wizard could make
Who was tired and caught on the hop
One piffling error, and then, to my terror,
I found myself facing the chop.
Alas for the eve when I met Lady Grieve
A-strolling the park in the dusk!
She was of the belief I could straighten her teeth
Next moment she'd sprouted a tusk.
Students began to giggle at the overly dramatic ghost. At first he looked extremely miffed, as if his little song wasn't going at all the way he wanted, but then he took advantage of the giggles. His tone changed, and his song became comical.
I cried through the night that I'd soon put her right
But the process of justice was lax;
They'd brought out the block, though they'd mislaid the rock
Where they usually sharpened the axe.
Next morning at dawn, with a face most forlorn,
The priest said to try not to cry,
"You can come just like that, no, you won't need a hat,"
And I knew that my end must be nigh.
The man in the mask who would have the sad task
Of cleaving my head from my neck,
Said "Nick, if you please, will you get to your knees,"
And I turned to a gibbering wreck.
"This may sting a bit" said the cack-handed twit
As he swung the axe up in the air,
But oh the blunt blade! No difference it made,
My head was still definitely there.
The axe man he hacked and he whacked and he thwacked,
"Won't be too long," he assured me,
But quick it was not, and the bone-headed clot
Took forty-five goes 'til he floored me.
And so I was dead, but my faithful old head
It never saw fit to desert me,
It still lingers on, that's the end of my song,
And now, please applaud, or you'll hurt me.
The laughter and applause filled the Great Hall as Nick seized his left ear and pulled. His whole head swung off is neck and fell onto his shoulder as if it was on a hinge. Looking pleased at the stunned looks on their faces, Nearly Headless Nick flipped his head back onto his neck, coughed, and said…
It was kind of tricky to fit together, but I think that I did okay. Hoped that you liked it! Please review!