Through the Green Glass Door

[Shadowcliff]

In this game, you figure our how to get through the Green Glass Door by pretty much guessing. You guess one thing that can go through the Green Glass Door, and one thing that can't. Then I will tell you if you are right or wrong.
For example:

MP3Player: A garbage bin can, but trash can't?

Shadowcliff:

That is incorrect.

!!!: A classroom can, but a student can't?

Shadowcliff:

That is correct.

I also have a few rules:

1. If you figure out how to get through the Green Glass Door, you must not tell anyone else.
2. You must not use another's solution to get throught the Green Glass Door.
3. You cannot give somebody a solution.
4. I will tell you if you are correct, unless I let somebody else do that job (which I probably will).

Have fun! I'll start with a clue.

Will can go through the Green Glass Door, but Bob can't.

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List of people who went through:
1. Shadowcliff
2. !!!
3. V3T_ddrultramix3
4. mike2727
5. Litodude
6. ninjaKIWI
7. peckerxcore
8. crzy99
9. GamerShadow
10. sc979
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Please ask me to clarify anything if nessecary.