In Super Mario 64 for the Nintendo 64 there is a pedestal in a pool in the courtyard behind the castle (where the ghosts are). If you read the plaque on the pedestal, it says "l is real 2041". L of course stands for Luigi, and 2041 is rumored to be the exact number of coins in the game. This has fueled the hunt for the non-existent Luigi in Mario 64. One code I heard involved finding all 2041 coins then completing 64 laps around that pedestal. People actually try this and others.