Metal Gear Solid Easter Egg - Meryl's Underwear & Other Tricks

Meryl's Underwear:
First of all, in any new game of Metal Gear Solid, it is possible to see Meryl in her underwear. Go to the level B1 lock up area where you rescue the DARPA chief. In the ventelation system you can look throught the vents and see Meryl, and the DARPA chief respectively. Look at Meryl only, then crawl back out of the vent. Crawl back in and instead of doing sit ups, she will be doing one-handed pushups. Exit and enter again, she will be doing leg stretches. Enter and exit again and she will be doing situps, except this time, she will not be wearing pants! Keep entering and exiting to watch her whole excercise regime in her underpants. After that, she'll be wearing pants again.
Meryl's Underwear 2:
When you rescue Otacon from Ninja, you will have to find Meryl again. She is dressed as a Genome soldier patrolling the office in the middle floor of the nuclear warhead storage compound. She is usually on the right side, but if you are in doubt, listen for her "cute walk" her thighs rub together when she walks and makes a "zip-zop" noise. Make sure she sees you. She will make the startled soldier noise, but it will be her voice saying "huh?" Follow her to the women's restroom. If you are right on her tail, and you run immediately to the last stall, you will catch her before she has had a chance to fully dress. She will do the next cut scene entire pantsless! These Konami programmers have no shame!

Other Fun Stuff:
Angry Mei Ling:
Call Mei Ling on your codec several times without saving. Eventually, she will stop talking to you. Keep doing it and her character portrait on the codec screen will stick her tongue out at you. Cute.
Running without making noise:
If there's an area where you'd like to run without making noise (like a loud floor grating or something) equip a weapon, then unequip it using the R1 button. Press this button rapidly while moving and Snake will appear to "glide" over the floor, silently!
Puppy love:
After going through the wolf cavern for the first time, Meryl will be on the other side. Get close to her and equip one of your cardboard boxes (remember which one) so that it is ready to go with L1. Quickly punch Meryl, then hit L1 as fast as you can to hide in the box. She'll whistle to call the wolves to attack you, but instead, they will sniff the box and urinate on it. The advantage here is that when crossing the cavern later in the game, if you are using the box, the wolves won't attack you.

Time Consuming Tricks, but fun:
The name is Snake; Solid Snake:
To get Snake to wear a tuxedo throughout the whole game, you must start a new game, and beat it without submitting to Ocelot's torture. This will result in the "Meryl" ending. At the end of the game, save the finished game status to your memory card, it should say "Docks" in red print. In this saved game, you will have the Bandana from the start, which gives you unlimited ammo when equipped. Start a new game from that save point, this time submit to Ocelot's torture and get the "Otacon" ending. Save the finished game and the new one should have both the Bandana, and the Optic Camoflauge from the start. Finish this game with whatever ending you like, and save the finished game data. In the new game, after boarding the elevator, and removing the swimming gear, Snake will be wearing a Tuxedo! Also, Ninja will be red instead of blue and white (just try to imagine Spider-man's color scheme)!

Happy Hunting!