1.

Now we're really up the creek!

B.    In a bad situation.

up the creek is a slang term for "in trouble, in a problematic situation".

2.

In my opinion, she's round the bend.

A.    Crazy.

round the bend is a slang term for "insane, crazy, mentally irregular".

3.

Explain it to me again from the top.

A.    From the beginning.

from the top is a slang term for "from scratch, from the very beginning".

4.

Why did you do it? – For kicks.

B.    For pleasure.

for kicks is a slang term for "just for fun; for mere pleasure or entertainment; for no good reason".

5.

The washing-machine's on the blink.

B.    Not working normally.