1. Information about or the solutions to questions of a test or exam written on a piece of paper or other document, which may be used for cheating, studying, or by someone grading said exam. Usually pluralized. Jim was caught using crib notes during his test and failed the course as a result. My friend gave me a great set of crib notes to use while studying for my final exam.

2. Complex or difficult information summarized on a document so as to allow for easy reference and/or understanding. Usually pluralized. I made some crib notes of everyday Japanese phrases so I would know how to say at least a few things while in Tokyo next week!