At the special features menu, highlight the button that would take you back to the main menu. From there, go up and the gingerbread man's buttons will be highlighted. Press enter or select and the gingerbread man will make a small noise.
Trivia
Select the "Special Features" option on either disc. Highlight the "Main Menu" option, then press Up to highlight the candy buttons on the gingerbread man. Press Enter to bring up trivia about the movie. Repeat this to see more information.
