cakewalk

something very easy
Example:

The exam was easy - a cakewalk.
call

a decision, prediction
Example:

We've given them the project details, it's their call now.
call the shots

to be in charge
Example:

Marco Trochetti Provera calls the shots at Pirelli.
can of worms

a complex set of problems
Example:

I don't know how we can solve the problem - it's a real can of worms.
can't win 'em all

can't be successful at the time
Example:

Well, we got the IBM contract, but not the Acer job. Can't win 'em all.
carcass

a person's body
Example:

Move your carcass and let me sit down!
card

someone who makes you laugh
Example:

Jim is a card. He just comes in the room and everybody laughs.

carry weight

someone who has influence
Example:

John's the one who carries the weight around here. He makes all the important decisons.
carved in stone

something that cannot be changed

 

The dress code is carved in stone. You wear a tie or you don't work here.