Did you know how the Konami Code exists?

[Nyu]

Did you know that Kazuhisa Hashimoto, who helped create the home-port of Gradius, created the Konami code because he couldn't beat the home-port of Gradius. He created the code to give him the goods, but he forgot to remove it when they released the game.

Sources:
From 1Up.com
From Tech Republic