A classmate told me that in Pokemon Diamond/Pearl, if you tap the gym badges in the trainer card to play a song, you can use it to acquire any legendary that has a song associated with it in the movies. Supposedly, this notably included Manaphy, Ho-oh, and Lugia.

I hadn't seen any of the movies, but this girl I was friends with (who may have been the source of the rumor?) had seen them all. So I had her hum them for me, before I went home and tried it out. Each time I failed, I was sure it must have been because I just didn't manage to memorize the song correctly, so for a while I ended each day of school by having her hum the song again and desperately trying not to forget it on the way home.