At the Pennant Collection screen, press Z+A and the enter code screen will come up. Put in the following codes to unlock hidden pennants:
Thanks: 1st and 15-This pennant forces your opponent to gain 15 yards for a first down.
For: Blink-This pennant causes the ref to spot the ball short for your opponent.
Registering: Boing-This pennant increases your opponent's chances of dropping passes.
Tiburon: Crossed the Line pennant
EA Sports: Cuffed pennant
NCAA: Stiffed pennant
Football: Take Your Time pennant
2005: Thread the Needle pennant
Killer Nuts: Unlock Ohio State All-time team