be in (one's) good books(redirected from be in their good books)
be in (one's) good books
To be regarded favorably by another person. Maria has been in my good books ever since she stayed late to help me finish that project. If you want to be in the teacher's good books, try to participate more in class.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.