Blow horn: Press B.
Whistle: Press A.
"Pow!": Press R.
"Whew": Press L.
Select any team and wait until the coin toss. If the outcome is heads, then around 98% of the time the next coin toss will be tails. Press Start and end the game. Pick the team again, then pick tails at the coin toss.
Choose your teams and choose to be the home team. When the other team is choosing, continuously press L + R until the referee announces the results of the coin toss. Around 99% of the time, it will be the opposite of what the other team picked.