Press Circle at the course selection screen.
Enter HARESO as a password.
Enter NAMOPI as a password.
Enter SECARE as a password.
Enter PORASO as a password.
Enter POQAKI as a password.
Shoot an eagle on any hole to unlock forged irons.
To unlock the entire set of forged clubs, get a hole in one on any hole.
Three consecutive birdies unlocks the following three bonuses (in order):
Forged Irons, Titanium Driver, and the Rubber Face insert putter. Between
each one of these, a set of three consecutive birdies goes to a special
ball (power ball, eye ball, mystery ball, etc.).