sign up for = register for
You must sign up for at least 12 units in order to be considered a full-time student.
 be cut out for = be suited to
I guess I`m just not cut out for physics.
 talk out of = dissuade, convince someone not to do something
I really hope you can talk George out of quitting his part-time job.
 kick around = discuss
Can we meet Monday to kick around the problem?
 figure out = understand
I can`t figure out this math problem.
 chew out = angrily point out someone`s mistakes
My father chewed me out for coming home so late last night.
 on cloud nine = feel extremely happy
I`ve been on cloud nine ever since I found out my paper was accepted for publication.