The story
The code was created by Kazuhisa Hashimoto. It was first used in the 1986 NES port of the arcade game Gradius, published by Konami.
Etymology from Wiktionary, CC BY-SA 4.0.
Konami Code
Today it means: A cheat code that appears in multiple video games and in popular culture, consisting of the key presses ↑↑↓↓←→←→AB. Full definition →