Scary Buns (In Japanese, Manjyuu kowai) is a rakugo story, or to be specific, a comic story.
History
Manjyuu Kowai was first heard in year 1776 (5th year of Anei era), published as one of the rakugo stanzas along with Jyugemu and Meguro no Sanma.
It was played in many stage dramas, mainly as a comic story.
Overview
The comic story starts with a gathering of a few youngsters who are free, and each of them started talking about thing they feared most : Snakes, spiders, or even ants. One of the youngsters laughed at them, calling them pathetic for fearing such trivial stuff. The others then proceed to counter that certain guy by stating "No such thing as fearing nothing!", followed by forcing the guy to spit out one of his fears. He then followed by "actually I have one", which is buns.
He then stated his reason "Just talking about bun makes me feel bad", and leaves the room to sleep at the room just beside the current one.
The offended youngsters then decided to teach him a lesson, and gathered some money to buy a pack of buns to scare him. To do so, they bought the buns, and put it around him. To prevent him from escaping, they locked the door as well.
Soon, a scream was heard and the youngsters went to check it out, only to find out that the man ate off all the buns.
"Ahhh, so scary, so scary that I had to eat them all!", "Too delicious it's scary!"
The result ended up making the group of youngsters even more angry, and asked "Then what is the thing you feared most!!?".
This time, he answered "Well at this area, rich tea is by far the scariest", and the story ends there.
Usage
This tag is mainly used for artworks that are so good/delicious/wonderful to the point it's scary. With the saying "One wrong step and you'll be on the road to death, but it's not about being so scary that you'll be scared to death, but you'll die of diabetes..."
It's similar to "HNNNNGGG" in the western fandom.