Pleasure Island was a cursed amusement park seen in Pinocchio. The park was owned and operated by The Coachman, who made a fortune from his crooked deeds, and is seen in the film when the Coachman brings Pinocchio, Lampwick and a coachload of other boys to the park. It is implied to be an illegal theme park, hinted by Honest John during the meeting in the Inn.
On its surface, Pleasure Island seemed like any other amusement park, except that it was one where the young boys brought there by the Coachman were encouraged to behave badly. Among the places where the boys could misbehave were the Roughhouse, where they were encouraged to fight, the Model Home, which was open for vandalism and destruction, and food, alcohol and tobacco was made freely available.
The park was designed so that little boys would "makes jackasses of themselves," and quite literally so. After enough time in the park, the boys would gradually transform into donkeys; still with their human minds, but donkeys in every other way. These donkeys were then stripped of their former clothing by the Coachman and placed into crates where they would eventually be sold to the salt mines, the circus and other places. Some of the donkeys did not immediately lose their human voices, and were placed in a pen by the Coachman - what happened to them next was unclear, although presumably they were either kept there until they finally lost their ability to talk, killed by the Coachman, or were used to pull his stagecoach. The curse apparently only affected little boys, as the Coachman, his minions and Jiminy were not affected.
Also, the evil influence of the island seems to wear off if the visitor is lucky enough to escape in time. Pinocchio's transformation stopped after he fled the island.
Pinocchio narrowly avoided being transformed into a donkey, and escaped with just a donkey tail and ears. However, Lampwick and all the other boys were not so lucky, and transformed into donkeys in one of the most notably terrifying sequences in Disney history.
In the original Italian story of Pinocchio, Pleasure Island was called Toyland ("Il Paese del Balocchi"), but in an early English translation it was mistakenly translated as "Boobieland".