Konami Code-like easter egg?

I am making a “never-ending” elevator game, and I want to implement the Konami code to get a badge and unlock something, like the UTG (Untitled Tag Game) trail. How would I implement this into my game?

Could you please retrieve examples to help your case?

Like that one trail you can unlock in UTG by doing (up arrow, up arrow, down arrow, down arrow, left arrow, right arrow, left arrow, right arrow, b, a, enter) and also gives a badge.