A one-time Interaction

i call this idea a "single - time" interaction.
i like this idea very much.
Heine/Lenz/Zizka is a design firm in germany.

they have moved in 2004. below we can see 2 business cards of them.

one with the old address (the first one), the other with the new one(the second one).
we can remove the gray area with a coin ,
then appear the new address.

the idea is very simple, but strong!
i wish, every design of mine can like this :-)