I wish I had a hoverboard.
Granted. You take the hoverboard out for a test run, and are soon an expert, performing fantastic tricks and nearly flying using the anti-grav technology. Unfortunately, you jubiliation lasts all of ten minutes, because you are captured by CIA agents and taken to a secret camp in Texas, where you are harshly interrorgated about how the hoverboard works and how to use it. You say you don't know how it works, and that you simply wished for it, and got it. A frustrated guard takes out his M-16 and shoots you. You die, and the secret of the hoverboard dies with you.
I wish I had a $15 iTunes card.