For example, at the state pedagogical university we have a very kind lecturer on geometry. Nevertheless, on exams he might be strict. So, one day there was an exam and one girl hadn't prepared properly. She became confused and didn't know what to say (in spite of that fact that she was very intelligent person), so the lecturer just asked her in a kind voice to go downstairs to the refectory and drink some coffee (well, of course, it was a hint to look through the notebook outside the class).