Creative product to sell?

It can be made up like a magical pill that teleports you to places, or it can be something realistic like a simple energy drink. Usually products that a group can make, and are simple, usually work the best though. We need to make and ad and presentation. One idea another group did a few years ago was attach a bin to a toy car so they could move the bin around with a remote. Ideas simple and easy to make like that work well but we can't steal that. Any good ideas? It can be something stupid, but people still have to want to buy it. It's a school project.