It is an acronym for Class-Responsibility-Collaboration, too.
This comes from an technique used in Object-Oriented Analysis and Design (OOAD) called 'CRC-cards'.
CRC-cards were invented by Ward Cunningham (he got famous for inventing the wiki) and Kent Beck in the late 80ies. They were working at Tektronix (Portland, Oregon) back then.
How does it work? You use small cards of which each one represents a class. Instead of writing attributes and methods on that card, you put responsibilities and collaborations on it.
A responsibility is a description of the classes purpose on a higher level.
A collaboration is understood as the class(or the classes), which is (are) necessary to fulfill the responsibility.
The main advantage of CRC-cards is, that they can be rearranged and reordered very easily. If you and your teammate have to discuss something regarding the class-model of your application, it is easier to use the cards then to draw large diagrams on huge pieces of paper. In discussion, you often get to the point, where you have to change the design radically, which is not easy if all classes are on the same sheet. :-)
Another advantage is, that the designer has to think on a high level of the classes usage and so it resembles "The Real World" much more.