Over The Hedge: Hammy Goes Nuts Codes -

Challenge mode:
Successfully complete story mode.

Sound Test option:
Successfully complete the "Ozzie's Trek" level in Story mode.

Play as Stella:
Successfully complete the "Depelter Turbo" level in Story Mode to unlock Stella for purchase for 70 nuts.

Play as Penny:
Successfully complete the "Try, Try Again" level in Story mode to unlock Penny for purchase for 140 nuts.

Backyard Cup in Arcade mode:
Successfully complete the "FANtastic" level in Story mode to unlock the Backyard Cup for purchase for 210 nuts.