Disclaimer: I don't think this really does anything, but in case it does, I don't own any of the stuff I'm going to write about.
Five-year-old Ron was playing with his teddy bear. He had asked everyone else to play with him, but his parents were too busy, his older siblings too mean, and his younger sister too annoying. So he and Ted the teddy bear were the only ones playing. They were playing a game that neither player really understood. It was simply the imaginings of a child that made no sense to anyone but him.
Stomps on the stairs made Ron look up just as Fred and George barged into his room.
"Hey Ron, do you like spiders?" asked George(or Fred? Ron was pretty sure it was George).
"No. They're scary. Especially the big hairy ones." Ron replied innocently. Even though he was only five, Ron knew how "funny" Fred and George could be. He never suspected a thing when they asked him about spiders however.
"Oh. Okay then." George said, smiling. Fred looked at the bear in Ron's arms and smiled too. Ron looked at Ted just because everyone else was. Ted the teddy bear suddenly turned into a big hairy spider, exactly like the ones Ron hated and feared. Except this spider was Ted-sized, and much bigger than any ordinary spider Ron had ever seen. Ron started to cry. Fred and George started backing out of Ron's room.
"Bye Ron," they yelled as they slammed the door shut and ran away. Ron screamed and ran to the other side of the room, far away from what used to be Ted. Mrs. Weasley meanwhile, was downstairs doing some dishes leftover from breakfast, and starting to make lunch. She heard the stomps, the yells, the slams, and the scream, and wondered what on earth was going on. She went upstairs to investigate. She passed Fred and George on their way down, who tried to look innocent when they saw her. She said nothing but had a feeling whatever was happening was going to involve them. Mrs. Weasley climbed all the way up to Ron's room, where she heard the cries and screams of a very frightened child.
She opened the door and saw Ron cowering on his bed, watching a giant spider crawling around on his bedroom floor. He saw his mother and yelled, "Mummy! It's a spider, a spider!"
Mrs. Weasley immobilized it and asked where it came from. Ron said it used to be Ted, but Fred and George made Ted go away and be big and scary and mean. Mrs. Weasley changed the spider back into Ted and gave him back to Ron. Ron looked a little reluctant at first, but he soon decided that Ted was nice and normal again. Mrs. Weasley went down to the twins' room and knocked on their door. When Fred and George opened it and saw her face, they gave identical scared smiles and took a step back. They were in big trouble.