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.
"Desert of Dread: Uncovering the Horrors of the High Desert"
One of the most infamous horror stories from the high desert is that of the "Devil's Highway," a stretch of road in Arizona that was once a major route for travelers. According to legend, this road is cursed, and those who travel on it are doomed to encounter all manner of horrors, from ghostly apparitions to mysterious creatures. The road has been the site of numerous accidents and fatalities over the years, adding to its reputation as a place of dark energy. horror in the high desert exclusive
There are numerous reports of ghostly encounters in the high desert, from apparitions seen on desert roads to haunted mines and abandoned towns. One of the most famous ghost stories from the high desert is that of the "Vanishing Hitchhiker" of Route 66, where drivers have reported picking up hitchhikers who disappear from the car before reaching their destination. These encounters often leave witnesses shaken and wondering if they've really seen what they think they have. "Desert of Dread: Uncovering the Horrors of the
The high desert is also home to numerous reports of cryptid sightings, including Bigfoot, the Mothman, and other mysterious creatures. These creatures are often described as being huge, hairy, and elusive, and are said to roam the desert landscapes, preying on unsuspecting travelers. While there's no concrete evidence to prove the existence of these creatures, the stories surrounding them have become an integral part of high desert folklore. There are numerous reports of ghostly encounters in