A hidden feature in these Pokémon games is the ability to tell a certain NPC four specific words or phrases using the easy chat system in order to unlock special rewards. Which words are required are unique per save file.
In Diamond, Pearl, and Platinum these rewards include 8 different special PC box wallpapers. The NPC to speak to is located on the 3rd floor of the Jubilife TV station.
In HeartGold and SoulSilver, rewards include 8 different PC box wallpapers plus 3 different Pokémon eggs. The NPC to speak to is located in the Violet City Pokémon Center.

The original distribution of these passwords was via the Pokémon Daisuki Club, a defunct, Japanese-exclusive official fan club website.
Below is both a calculator to generate the passwords for your specific save file, an in-depth explanation of how the password check system functions, and a full dump of the relevant word data.
: Featured prominently as the main attraction, with a massive variety visible throughout the shop.
: Welcoming and professional, suitable for those looking to discover new wines in a cozy environment. Falis, Lisbon, Portugal Falis mi
Based on current reviews, in Lisbon is a highly-rated wine bar known for its intimate atmosphere, extensive wine selection, and exceptional service. It is currently a recipient of the Travelers' Choice award on Tripadvisor, placing it among the top 10% of global listings based on traveler feedback. Key Highlights : Featured prominently as the main attraction, with
: Reviewers consistently mention that the staff is "fantastic," "friendly," and provides "excellent" service that often exceeds expectations. Food & Drink : It is currently a recipient of the Travelers'
: Popular small bites include high-quality bread and olives, with portions described as "generous". Venue Details Location : Lisbon, Portugal. Category : Wine Bar / Tapas.
: The bar is described as a charming, floor-to-ceiling bottle-lined space located on a quiet corner in town. It is frequently praised as an ideal spot for a drink before dinner or a relaxed evening.