Be in for it
Definition 1 of 1
Pro Tip 1/3Expect Trouble
Used when someone anticipates negative consequences due to their actions or situations. 
I forgot our anniversary; I'm really in for it now.
Pro Tip 2/3Colloquial Warning
It's a casual way to warn someone they're likely to face problems or punishment. 
You broke the vase? Oh, you're in for it when Mom sees this.
Pro Tip 3/3Imminent Consequences
Indicates that someone is about to face the repercussions of their actions very soon. 
She's seen your report card. You're in for it now.