There once was a 2D space shooter called Gradius that was so damned difficult it utterly mocked the concept of fun. Kazuhisa Hashimoto discovered this fact while working on an NES port of the arcade, and since he was basically god of an electronic world he came up with a easy to remember input sequence that maxed out your ship's power-ups so he wouldn't keep dying. Then like the real God did with nipples on men, he forgot to take it out for the release.
Since the sequence has achieved a pop culture life of its own, and if you're just wandering around the world you'll find it like clues left behind in a Dan Brown novel. Here's our top 10.
10. University of Minnesota Solar Vehicle Project: Inputting the sequence on the home page (using Enter for Start) brings up a picture of a walrus named Leroy. I have no idea what this means or how it relates to solar cars, but a little Internet snooping has found Leroy spray painted in other places as well.