Up, up, down, down, left, right, left, right, B, A. To some of you, this will mean nothing, but I bet if you’re an old-school Nintendo gamer, your ears just perked up. It was a cheat code used in several Konami games, but most notably, it gave you 30 extra lives in Contra. This super-secret (…or not) code has a special place in the hearts of geeks who have since grown up and used it to code fun stuff in their websites. Here are 10 of those websites – I’ll tell you where to go, but I won’t tell you what it does until after the jump. That way you can try it for yourself if you want, but if you don’t have time or happen to be somewhere with restricted access you can still be in the know. Here goes:

1. This one is my favorite. Go to the GeekStuff website and enter the code. If you’re at work, don’t do it without headphones (unless you work someplace really cool).

2. Enter it in Google Reader.
This only works if you are signed in, so if you don’t have a gmail account… sorry. You can read what it does after the jump.

3. Double geek points for ActivateMedia for what the code results in. After you enter the code, you have to hit the enter key for it to work.

4. Darkscribes.org capitalizes on a certain Internet meme from a couple of years ago…

5. A little daily affirmation for you over at Lekevicius.com.

6. Even Marvel Comics gets in on the act. Press enter to activate this one as well.

7. It’s Shark Week every day at Qiwi. Keep hitting enter once you key in the code.

8. Some old-school Nintendo nostalgia for you at virtualNES. Enter to activate.

9. Just when you thought the bacon craze had reached its limits, SoundClick takes it to another level.

10. Fittingly, GameSpot.com has one too.

1. It’s the Teenage Mutant Ninja Turtles theme song.
2. It gives your sidebar a ninja theme.
3. You get to enjoy the Truffle Shuffle scene from The Goonies.
4. Rickrolled!
5. A pixilated Mario declares how awesome you are.
6. Squirrel dressed in Deadpool mask, which probably means something if you’re a Marvel fan.
7. Pictures of sharks continue to pop up every time you hit enter.
8. The old Nintendo World Championships logo comes up.
9. A slice of bacon is slowly chomped into nothingness.
10. Just in case you didn’t know the other Contra cheat codes, GameSpot links you to them.

You never know what site up, up, down, down, left, right, left, right, B, A, will work on. Rumor has it Newsweek even got in the act for just one day earlier this year – entering the code supposedly turned all stories to articles about zombies. This no longer appears to be active. If you’re like me, you’ll probably spend all weekend entering the code on every site you come across. Enjoy.