All things can go through the green glass door.

[Daedalus]

A dog can go through the green glass door.
An animal can't.
Do I win?

[Ad Bot]

[RedSaturn]

A computer can go through, but the froums can't

[TapeDeck]

Your mother can but a woman can't.

A dog can go through the green glass door.
An animal can't.
Do I win?

A computer can go through, but the froums can't

All wrong. 

Free stuff can but cheap things cant.

[Dippindots]

All wrong. 

Free stuff can but cheap things cant.

Tape got it too :D

[Regulith]

A secant but a tin can

[TapeDeck]

A secant but a tin can

Incorrect

'Correct' can but 'wrong' cannot.

[Daedalus]

A potato can but a French fry can't.

[Regulith]

Incorrect

'Correct' can but 'wrong' cannot.

Fine

A tin can but a secant*

[Daedalus]

A blue brick can but an orange brick can't?

[duke 838]

But everything can't.

This is one of those "Do you get it" things.

If you know any, post them here, I love these things.

Books can go through the green glass door.

But paper can't.

I hate these, our school counselor came in and made a few up, and every one said stuff and he was like yeah that can go through and i was like bananas and he was like no, why don't you guys explain why not i felt so loving stupid.

[pocketrocket300]

Your all doin it wrong.
A lamp can.
A lightbulb cannot.
Right?

[Daedalus]

Hmmmm...
A cow can, but milk cannot?

[Chrono]

Chrono can go through the green glass door.

But the Console cannot.

PARADOX

[pocketrocket300]

Hmmmm...
A cow can, but milk cannot?

Close, but not quite.  Insert credits.

[Daedalus]

Close, but not quite.  Insert credits.

:I
A fetus can, but a child cannot?