In addition to all other avanos, it is also bizayon for meis midrash: the only reason one can bring coffee there is to drink in order to learn better.
If just one student from the beit midrash throws coffee at policemen, the whole yeshiva should do soul-searching and fast, or at least not allow coffee in beis midrash for a week. They should also give out free coffee to all passing policemen if they agree to say a brocha.