Putty exam refers to an exam in which the teacher makes so difficult the entire class fails.  Putty exam指的是那种全军覆没的高难度考试，老师出的题太难，以至于全班同学都不及格。 Example: I better start kissing up after that putty exam.在这种高难度考试结束后，我最好赶紧巴结一下老师。