Halloween Special Woooooooo !!!!
If you'll wondering this takes place in the future
But it's fine if you read it because I won't spoil any plot points(duh)
Just a little bit of foreshadowing
( backshadowing ? presentshadowing ?)

Ok lets begin

3rd POV

"WHAT !!!!!" Blue screamed probably shaking the whole Underground

"Blue what's wrong ?!?" Stretch said running in from the living room to the kitchen with Pup right behind him.

"Red Just Told Me That He's Never Celebrated Halloween !!!!"

"w-well i-"

"Other Brother Please Tell Me That You've At Least Heard Of  Halloween !!!"

"Well me and Sans would cele-brate it once in a while but we wo-uld just watch scary
mo-vies and eat Pu-ddi.
I've never tri-ck or tre-at though"

"t-trick ó think ?"

"Trick Or Treat" Blue corrected "Its The Best !!
You Get To Dress Up In Magnificent Costumes And You Go To People's House's And They Give You Candy!!"

"f-for free ?"

"Yup every time" stretch answered

"Just imag-ine it like beg-ging for food and
peo-ple have to give you some-thing" Pup whispered to Red

"Halloween is actually a human holiday but when monsters came into the Underground they took the holiday with them" stretch informed

"w-wow that does sound cool"

"It Will Be Because It's Now My Duty To Make Sure You Two Have The Best Halloween Ever !!!!!!!!"

"Heh your so cool bro"

"Of Course I Am Now Let's Get This House Ready"

~Later~

The house was now full covered with cobwebs and Jack o lanterns

Blue had pulled their doubles into the living room to teach them some Halloween traditions

"Now We're Going To Carve Pumpkin's To Make Awesome Jack o Lanterns !!!"

"h-how do we do that ?"

"Glad You Ask !!!
First Cut Open The Pumpkin Then You Take Out The Seeds And Pumpkin Guts"

Blue open the pumpkin and scoped out the guts and threw them in a trash bag

"Now You Just Carve Whatever You Want On The Pumpkin"

He cut 2 triangles and a smile.

"You Then Add A Candle Or A Flashlight Inside And Your Done What Do You Two Think ???
Pretty Aweso-"

Blue looked up from his lesson to see their reactions.

Pup was aggressively puking into his trash bag while Red was curled up into a ball rocking and muttering to himself.

"O-Oh Dear Papyrus !!!! We Might Need Some Assistance !!!"

"What's wrong bro- oh dear..."

"They Just Started Freaking Out !!"

"Hey Red buddy what's wrong ?"
Stretch asked kneeling beside Red

"h-he k-killed i-it !!!!!!!!!!!!!"

"Oh boy"

~Le Time Skip~

After a couple of snuggles Red had calmed down enough for Stretch to explain the situation.

Luckily Red understand but was still a bit shaken up.

Pup had luckily stopped vomiting and was just recovering.

"U-Uh Why Don't We Do Something Else
Oh ! We Could Make Our Costumes !!!"

"Does it inv-olve kill-ing and or invad-ing
some-one's personal bubb-le ?"

"No ! Wet just going to make costumes nothing to freak out over"

"Th-at's wh-at you say"

~Time Skip Brought To You By Error~

The group had finally finished their costumes

Blue was a wizard
Stretch was a witch
Red was a black cat
And Pup a werewolf

"Wow-ie this is co-ol so now wh-at ?"

"Now We Go Around Snowdin And Ask For Candy !!!"

"Oh boy"

~Time Skip Brought To You By Ink~

In town the group went around collecting candy

"Ok Guys When You Ask For Candy Your Suppose To Say Trick or Treat"

"g-got it"

"So wait th-ey just give us the can-dy ?"

"Yup that's about it"

They walked up to the house and knocked on the door

A bunny monster answered the door

"trick or Treat" Red Pup and Blue yelled

"Oh such lovely costumes
Here you go"

"Tha-nk you !!"
"Thank You Madam !!"
"thanks"

"Come On The Next House Awaits !!!!"

"o-okay !!"

"Guys wait up you kn-ow I-I can't run that
fa-st !!!"

"t-that's because your a lazy bones"

"Am not-t !!!"

"Their a cute bunch aren't they Papyrus ?"

"Yeah they really are"

Stretch POV

I allowed them to continue on their own and after an hour they returned home.

"Hey guys how did it go ?"

"It Was The Funniest Halloween I've Ever Had !!"

"Heh cool bro and what about you two ?
Did ya have fun ?"

"It was the be-st I really ho-pe we can do it
aga-in so-on"

"i-it was fun but *yawn* i'm hoping we can go to bed already"

"Yeah it is pretty late why don't we just hit the hay ?"

"i-i wheat-ly like that idea"

"Oh No Not The Puns !!!"

"Hay we shouldn't make puns around Blue you know he can't barrel them"

"Nooooooo !!!!!"

~Time Skip~

I was in bed when I felt someone on me
"Red ?"

"c-can i sleep here for the night ?"

"Heh of course"

He got in bed and immediately started snuggling me

"Good night Red"

"zzzzzzz"

Happy Halloween
I hope you enjoyed and are having a wonderful Halloween
Stay safe
Bye :)