Metal Gear Solid 3: Snake Eater/Secrets

The following is a rather disorganized collection of fun secrets in the game Metal Gear Solid 3: Snake Eater released for the Playstation 2 in 2004 by Konami. As with many other articles posted here, be warned of spoilers. This is by no means complete.

The Survival Viewer
 * Open the Viewer and press R1 to enter Full View mode, where you can use the two analog sticks to rotate and move Snake's image. Spin him around a bunch of times with the right stick (probably at least 15 revolutions, I haven't counted), then exit the Viewer. Snake vomits on the ground in front of him and loses one-fourth of his stamina.
 * In the Cure window, you can trigger a few different poses from Snake by exiting and re-entering the X-Ray mode (R1).
 * Near the end of the game when Eva is following you, open the Cure window and select her from the list - then spin her around a few times in the full view mode. Just like Snake, she'll vomit on the ground and lose some stamina.
 * Look at Eva's medical history (in her Cure window, press R1, then R2). There are some odd entries in there, including breast implants.
 * Her food history contains similarly odd entries.

Major Raikov
 * If you grab and interrogate Raikov (it's usually easiest to do this while he's hiding in the bathroom), he'll tell you that Colonel Volgin hates water, and that he hates the glowing mushrooms. This might not make sense at first, but when you're fighting Volgin, you can throw Russian Glowcaps at him and shoot the water lines to weaken him.
 * If you kill Raikov instead of tranquilizing him, you'll see him again during the encounter with The Sorrow - running down the river and covering his private parts. Much like Raiden in MGS2.
 * If you contact Eva while wearing your Raikov disguise (the officer's uniform and the Raiden mask), you'll discover that the guards will question none of your actions so long as you are disguised as Raikov. Even if you punch them in the face, grab and throw them, or kick them over.

Snake VS Monkey
 * The introduction to this game mode makes a few references to other games - notably in Snake's line, "Why don't you let Sam or Gabe do the job?" - where Sam and Gabe are Sam Fisher and Gabe Logan, from the games Splinter Cell and Syphon Filter, respectively.
 * This entire mode is essentially a parody of the Ape Escape series.

Unlockable Weapons and Items
 * Patriot Assault Pistol - Defeat The Boss by knocking her out.
 * Mosin-Nagant Tranquilizer Rifle - Defeat The End by knocking him out.
 * Colt Single-Action Army at game start - When Ocelot challenges you to a duel in the end of the game, pick the gun on the right.
 * Tuxedo Outfit - Complete the game once, save when prompted to at the end, then reload your saved game. When you start the game and retrieve your backpack, you'll have the Tuxedo in your Survival Viewer.
 * Cold War camo - Defeat Colonel Volgin by knocking him out.
 * Moss camo - Sneak up behind The End and hold him up three times. (?)
 * Spirit camo - Complete the battle with The Sorrow (?)
 * Stealth Camouflage - Complete the game without being spotted. Alternatively, find and shoot all 64 of the toy frogs found throughout the game.

Silly Moments
 * Equip the Tuxedo during the Virtuous Mission and contact The Boss.
 * Wear any cardboard box and contact Sigint.
 * Equip the Naked camo and contact Sigint.
 * Pick up a Russian Glowcap and contact Para-Medic.
 * Eat the Russian Glowcap afterwards and contact Para-Medic.
 * Equip the Chocolate Chip camo and contact Sigint.
 * Save your game while you're being jailed in Groznyj Grad.
 * After loading your game and playing the short "nightmare" minigame, contact Para-Medic.
 * After contacting Para-Medic, contact Sigint as well.
 * While being held in Groznyj Grad, wait for the guard to give you food - then pick it up and through it through the hole in your cell door. Once you've fed him three times, he'll rush to the bathroom in a scene reminiscent of the cell guard from MGS1.