It is shown on this site - http://www.cheatcc.com/ps3/metalgearsolid4gunsofthepatriotscheatscodes.html
First you need to play the levels to collect the items.
Pure silver or solid silver is almost a perfect metal. Regular silver is a sliver with other metals added to to increase the luminosity of the silver.
There are no game cards but Bonus or Collectors items are available by typing /bonus
Obtuse means that an object is not clear at all and is a solid color. Items such as wood, metal, and bricks are obtuse.
There were two "treasures" (bonus items) in Poptropica. They are no longer available. For the list, and any current bonus items, see the related question.
There are no rewards for beating Metal Gear Solid 2: Sons of Liberty with 30 dog tags. For the Tanker Chapter, you can collect 33 dog tags for the Infinite Ammo Bandana, and 78 dog tags for Stealth Camouflage. In the Plant Chapter, you can collect 100 dog tags to get the Brown Wig, which gives you infinite ammo, 120 dog tags for the Stealth Camouflage, 170 dog tags for the Orange Wig, which gives you an infinite hanging meter, and 218 dog tags for the Blue Wig, which gives you an infinite O2 gauge.
The brand that makes the best camouflage seat covers is the Coleman brand. Coleman is the industry leader in providing gear that is used for hunting and as a lateral business move has added many accessory items in the camouflage design. The camouflage seat covers is a new addition to the Coleman outdoor gear brand and that is where the items can be purchased.
Not much. A solid metal hammer or a cast iron skillet, perhaps. Or a compact laptop computer.
No, they do not affect play in any way.
EPFTREASURE!
You can get a stolen mail truck which is a bonus item on Mafia Wars and you can buy some using reward points. You also can get more items when you reach level 99.
If the item is solid silver, it will have identifiable silver hallmarks stamped into the metal. You could also buy a small kit designed to detect plated items from solid silver.