How to call bullshit: "Speak up if you think what you're hearing is bullshit. Never tone it down or talk baby talk. Never mumble or apologize in the defense of reason. Don't bow to the sensitivities of others. Don't cower to political correctness."
This is some perilous advice. There are classes that are mostly just bullshit, best to weather the storm and learn how to regurgitate it on the test, it will help you in the working world when you need to make sure your TPS report has a cover sheet. When you get to a place of power you can get rid of the cover sheet on that TPS report.
Sometimes calling out bullshit can be pretty rewarding, pick and choose. Sometimes truth really isn't as important as making a coustomer happy or getting a good grade.