Done in flash of voldemort and the death eaters taking it upon themselves to create a great christmas
'Twas night before Christmas, and all Hogwarts slept,
Not even Filch down the corridors crept.
The stockings hung, the trees owl-decked,
Iggy's mistletoe on Snape's door: all checked.
The students were nestled snug in their beds,
Blissfully snoring all four of House Heads,
Lupin had finished a night's worth of prowling,
Old Fluffy finally quit with his howling,
When out on the lawn there arose such a clatter,
It made every stone in the old castle chatter!
Headmaster Dumbledore took just one peek -
The scene he beheld made his old knees go weak...
The moon on the breast of the new-fallen snow
Shone on the Dark Lord, his minions in tow.
"Merlin", he thought, "I should quit butterbeer!
Is that a sleigh pulled by... reindeer?!"
With a little old driver, so lively and quick
(Yes, I know it's Wormtail - I'm not THAT thick!)
All masked and hooded the Death Eaters came,
The Dark Lord then turned and called them by name:
"Now Lucius! now, Bella! now, Alecto and Crouch!
On, Amycus! Rabastan! Macnair! Don't slouch!
To the Gryffindor tower! To the Hufflepuff hall!
Ravenclaws, Slytherins... Get to them all!"
As dry leaves that before the wild hurricane fly,
Most collided mid-air (Peter got a black eye!)
Then, finally, up to the turrets they flew...
Laden with Bott's beans and Zonko's stuff too.
Then, in a twinkling, was heard on the roof
The sound of footsteps (DEs have no hoofs).
Wand at the ready, the Headmaster leapt...
Dark Lord himself out of fireplace stepped.
He was dressed all in fur, from his head to his foot,
(Is that a smudge or dried blood on his boot?)
The air in the chamber did stir and then crackle
As Dark Lord approached the old man with a cackle.
His eyes - how they twinkled! his dimples how merry!
(A Dark Lord with DIMPLES?! Oh Merlin, that's scary!)
And, as Albus pondered which hex to produce,
He reached in his robes and pulled out... Polyjuice?!
The stump of a pipe he held tight in his teeth,
A red hat above, bushy white beard beneath -
(Take a seat, darlings, and a deep breath, because...)
The Dark Lord now looked like that Muggle St Claus!
He was chubby and plump, a right jolly old elf,
(Chances are, the next day he'll Avada himself)
Poor speechless Albus barely managed to blink
As Dark-Lord-turned-Santa stepped up with a wink.
He spoke not a word, but went straight to his work,
Presenting Headmaster two socks with a smirk,
Then, shouldering oversized green velvet sack,
Dark Lord left the bulding with a single loud 'CRACK!'
He sprang to his sleigh, to his team gave a whistle,
(I'll bet my Time-Turner it made Malfoy bristle!),
Albus blew him a kiss ere he drove out of sight,
"Happy Christmas to you, Tom!" Dear gods, what a night...