Manchester United

Easy win:
When losing a game in single player mode, press the key to begin a two player game.
The CPU team will freeze, allowing an easy win.

Always save penalty:
When conceding a penalty, press Up on the Joystick hold Fire.
Your goalie will always save the shot.

Automatic loss:
Press [Ctrl] + [Esc] to lose with a score of 5-0.

Extra points:
Repeatedly press R after scoring to toggle the replay.
Another goal will be scored approximately 50% of the time.
Note: Sometimes, the opposing team will be credited with the goal.