Teddy bear

A teddy bear in the magical world seems to be the same sort of toy as in the muggle world, however they might have some magical properties. When Ronald Weasley was three years old, Fred turned his teddy bear into a "dirty great spider" because he broke his older brother's toy broom stick. This supposedly created Ronald's fear of spiders.

Behind the Scenes Fred was two years older than Ron. If Ron was three, Fred would've been 5. 5 year olds can't usually perform particular spells on purpose. However, Fred's anger might've prompted him to perform magic and it could just be a coincidence that it was a spider.