Post-it: Kate and William19

To celebrate White Day in South Korea (another romantic holiday a month after Valentine's Day), agency Innored and Post-it created a clever stunt that uses plenty of Post-its to communicate a man's affection for his girlfriend.

With more than 100 million users worldwide, Twitter has over the recent years not only become a phenomenon, but a widely accepted tool to send short message to each other. Just like when we text each other on the phone, but visible to anyone.