To be 'in for it' is an idiomatic expression meaning you expect to be in trouble or to be punished for something. 

1. I knew I'd be in for it as soon as I told my parents about my plans to go travelling. They think I should find a job and settle down.
2. I'm in for it if I don't hand in this paper on time. My professor penalises work that is handed in late.

1. I just got word that the boss has been told about our mistake and wants to see us in his office immediately. We're really in for it now!
2. We are in for it if that client doesn't receive their delivery today.