5. Big Head Mode - NBA Jam
How It's Activated: Hold Up, Turbo, and Steal at the "Tonight's Match Up" screen.
What It Does: All of the players on screen will have comically oversized heads. This is without question the most famous cheat on any sporting game - though the UFO abduction in the FIFA games comes pretty close - and proved above all else that the NBA Jam series never strived at all to take itself too seriously. Of the litany of bizarre cheats the game allowed you to enact, this was certainly the most entertaining, and when playing it as a youngster, I found myself activating the cheat 99% of the time, to the amusement of myself and my buddies I was playing with. Since then, Big Head Mode has been prevalent in myriad popular games, most memorably the N64's classic shooter Goldeneye, and also the newer iterations of NBA Jam.