Stoydi (shtoy-dee) is a Dutch bear from fictional Holland children's stories.
Stoydi was created by Jo & Twiggy from 96 Trent FM as a fictitious toy. It was part of a "social experiment" to see if parents and children would believe that an imaginary toy would be 'in demand' just through the power of suggestion.
Jo & Twiggy had people asking where they could get hold of Stoydi, and a fake website was created, which also generated feedback from people wanting to buy Stoydi direct from the manufacturer.
Despite an on-air apology, Jo & Twiggy have promised to do penance for the Stoydi-effect involving a charitable activity.
References
Stoydi Wikipedia(Text) CC BY-SA