Mission select:
Click LEFT ANALOG-STICK, press BLACK, R, click RIGHT ANALOG-STICK, press WHITE,
L at the mission selection screen.

Mission skip:
Click LEFT ANALOG-STICK, press WHITE, WHITE, BACK, click RIGHT ANALOG-STICK,
press WHITE during a mission.

Alternate music:
Click LEFT ANALOG-STICK(2), RIGHT ANALOG-STICK(2), press L, R at the title
screen.

Joke mission briefing:
Play missions 1, 3, 6, 8, 9 or 14, then press L, L, R, R, click LEFT ANALOG-
STICK, RIGHT ANALOG-STICK at the armory screen before launch.