"For shit" and "Cabin"
[Q1]
Please click the link bellow and please listen to a sister and brother's conversation.
http://www.youtube.com/watch?v=Vc6oLGSLgZw
At 00:12, the older sister says something.
I hear "Your memory is for shit" or "Your memory is bullshit" or "Memories for shit"
Which one is right? And as for "for shit" Does it mean "awfully bad"?
If so, these things bellow are natural to say? (I tried to make sentences with FOR SHIT)
● Your dress was for shit last night.
● I can't speak with you so long because my vocabulary is for shit.
● I didn't clean up my room for two weeks so my room has been for shit now.

[Q2]
In a certain movie, someone driving a truck said to another "You get in the cabin with him."
Now I have a question about the word "cabin"
I searched "cabin" in the dictionary and it says "Cabin is a small room in a ship or boat"
There is nothing about a truck or car but only "a ship and boat"
How do you think about it? You think the meaninig of "cabin" goes for a truck as well?

Question

"For shit" and "Cabin"
[Q1]
Please click the link bellow and please listen to a sister and brother's conversation.
http://www.youtube.com/watch?v=Vc6oLGSLgZw
At 00:12, the older sister says something.
I hear "Your memory is for shit" or "Your memory is bullshit" or "Memories for shit"
Which one is right? And as for "for shit" Does it mean "awfully bad"?
If so, these things bellow are natural to say? (I tried to make sentences with FOR SHIT)
● Your dress was for shit last night.
● I can't speak with you so long because my vocabulary is for shit.
● I didn't clean up my room for two weeks so my room has been for shit now.

[Q2]
In a certain movie, someone driving a truck said to another "You get in the cabin with him."
Now I have a question about the word "cabin"
I searched "cabin" in the dictionary and it says "Cabin is a small room in a ship or boat"
There is nothing about a truck or car but only "a ship and boat"
How do you think about it? You think the meaninig of "cabin" goes for a truck as well?

Answer

1. She means he has a very bad memory. (it's slang of course)You would not write the sentences as you did,you would only say it. In the UK we say "up to shit"
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2.cabin would be the front part of the truck where the driver sits.

Answer

About cabins:
http://en.wikipedia.org/wiki/Cabin_(truck)
You only use this when talking about the front part of a BIG truck. Here, we call them 18 wheelers or semis (http://en.wikipedia.org/wiki/Semi-trailer_truck).

Answer

In the US, we say "shitty" in the same way. That movie is a little old and the slang sounds awkward to me now. This is VERY offensive, so you would only say/text it in a casual setting with friends.
"your dress was shitty" "my vocabulary is shitty/for shit" "my room has been shitty" (the last one sounds a little awkward)