Weeder course
A weeder course, in theory, is a low-level required course difficult enough to dissuade prospective scholars from further study in the discipline, whether the completion of a major or application to grad school. For example, Organic Chemistry and Econometrics are supposed to be weeder courses.
At Columbia, however, nobody ever fails. Additionally, given the lack of formalized advising, a certain brand of masochistic student might actually be encouraged by a Gentleman's B-.