I once sold an idea over the phone. But the situation was very unique, and it required no R&D and no financial investment. It happened during the Tickle Me Elmo craze.

As Tickle Me Elmo was taking the country by storm, a ubiquitous yellow plastic sign was a popular item on the rear windows of cars. It read “Baby on Board.” My idea was to ride both product waves by printing an image of Elmo at the steering wheel, under which was the warning “Don’t Tickle Driver.” Cute, right?

Here’s how things went: I got on the phone and shared the “Don’t Tickle Elmo” idea with my partner, Richard Maddocks, a brilliant designer and engineer, who lived nearby. He made a sketch of the idea. Next I called a manufacturer of infant products in New York City and pitched the idea. I faxed the sketch. He loved it.

Within an hour, the manufacturer had called and faxed the sketch to a buyer at Toys R Us, who, upon seeing the drawing, promised an opening order of 25,000 units. We hadn’t even made a prototype! In fact, we never did a prototype. We simply bought some Baby On Board signs and mocked them up with our design. The manufacturing specs would be the same.

This was possible only because the concept was so simple that a baby could understand it and trusted personal relationships were in play—mine with the manufacturer and his with the retailer.

Another time I came up with an idea to miniaturize a working yo-yo to the scale of a key chain fob. This took a bit longer to license than the Elmo novelty, but again, I didn’t have to build a prototype. In this case, I called the presidents of Duncan and Basic Fun, respectively, shared the marketing concept, and affected the marriage. Duncan gave Basic Fun the rights to its trademark and some sample yo-yos. I worked with Basic Fun and its engineers to make it happen. Basic Fun went on to sell over 2 million units of Duncan Imperial and Butterfly yo-yo key chains.

The prototype of my best-selling board game Adverteasing cost no more than $25 to produce. I took some paper, markers, cards, and a scissors—voilà, I had a playable prototype. Adverteasing, still on the market, has sold over 1 million units, to date.

Once I made a seven-figure deal for a product that had no prototype, but that, as Kipling would say, is another story.

Clearly these examples are anomalies. They are also based on many years of trusted relationships. And you have to know when to play such cards. Normally I do use prototypes in presentations, even to my closest friends.