TheGameSite: Tips, Cheats, Walkthroughs: N64: FIFA Soccer 64
BOO YOUR OPPONENT CODE.
At any time during game play, press the control pad in any direction. You can only do this once per quarter.
SPECIAL SOUNDS
After a goal is scored, press:
C Up to play an air horn.
C Down to play a drum
C Left to play a different drum.
C Right to play a different air horn.
You can press them as many times as you like until the next kickoff.