Metal Gear Acid

Jehuty Card
Enter "JEHUTY" as a password to get a card featuring Jehuty from Zone Of The Enders. This card will destroy all equipment and equipment level-ups in the current room.

XM8 Card
Enter "XMEIGHT" as a password to get a weapon card with 50 attack, 60% hit, 5.56mm bullets, 6 shots, 70% reaction, move 6 spaces, knockback, and burn.

Mika Card
Enter "MIKA" as a password to get a card featuring Mika from Snatcher.

Bikini Model Clip
Enter "SABRAGE", "NOMEL", "ELYTS" or "MAEB" as a password to see clips featuring Japanese bikini models. Note: These will cause Snake to get a nosebleed, but has no effect on Teliko.

Karen Card
Enter "KAREN" as a password to get a card featuring Karen from Policenauts.

Bonus Cards
In the main menu, select Password and enter the following passwords:

Gives Card No.202 - Saitou Yuu | Elyts
Gives Card No.184 - Jehuty | Jehuty
Gives Card No.182 - Karen Houjou | Karen
Gives Card No.203 - Shibuya Eri | Maeb
Gives Card No.178 - Mika Slayton | Mika
Gives Card No.201 - Yoshida Asaki | Nomel
Gives Card No.200 - Kosaka Yuka | Sabrage
Gives Card No.173 - Viper | Viper
Gives Card No.199 - XM8 | Xmeight

Viper Card
Enter "VIPER" as a password to get a card featuring Black Arts Viper from the Metal Gear Solid on the Game Boy Color.