Lily had sent Dudley a stuffed koala toy when he was born. Petunia angrily threw it away, but Vernon found the koala in his son's crib a few days later. The koala was his son's favorite toy; even as an infant Dudley wouldn't sleep until the koala was in his crib.
His first word was "MINE," which he screamed when Petunia tried to wash the koala. (His second was "'oala," screamed when Petunia quickly gave it back.)
When he was three, Dudley decided he wanted a koala for his birthday. Marge insisted that there was nothing notable about a koala and told Dudley that what he really wanted was a dog. Dudley screamed "'OALA" for an hour, and Marge never attempted to give Dudley a dog again.
WC: 130
For the Return of the Daily Weird Prompt Thingy: "stuffed toy koala"; for the Hogwarts Writing Club Competition: "notable"