Up Down Left Right A & Start.
The easiest code to ever have graced a console.
So when you were younger (or even now) did you ever use any cheats on a game? I used a few exploits in my time (such as resetting the game when you didn't have all the Chaos Emeralds in Sonic) and when I found the internet I certainly gave the super sonic code a whirl, but that was pretty much the limit of my cheating.
My brother on the other hand was one who would always always check to see if there were any cheats even before trying the game, and it used to smurf me off to no end. One day he came in bragging he beat Kingdom Hearts 2 on Proud Mode... only he used cheats... it took a long time but I eventually convinced him it was much more satisfying to kill a boss at a low level/harder settings until today, when he dislikes anything if it is to easy.
I understand if you want to cheat to play a game, but you should at least try it before hand and wait till you get stuck before resorting to cheats.