let someone in for something—involve a person in smth. unpleasant; cause smb. to have trouble:
- The boy’s careless treatment of the car has let me in for a large repair bill.
Note: The expression does not correlate in meaning with the phrase put someone in for something—enter a person for an examination, contest, etc.:
- How many of your runners are you putting in for the race?
let someone in on something—make smth. such as a plan, agreement, etc. known to a person:
- He was let in on the arrangements without our consent.