The four stages of receiving a postcard usually goes something like this… Receive postcard, pretend to read postcard, place on desk, use postcard as a coaster. Thankfully, PostCups actually encourage this.
The postcards, created by designers Ink Julep and Jenn Perng, contain illustrations that are incomplete. It is only when the postcard recipient places their coffee on it and creates a coffee ring, that the illustration is complete. Whether you actually read the other side or not.
One pack contains seven illustrations. Check them out here.
[link, via Laughing Squid]