A proffessor or teacher who assigns a rather easy assignment, such as an Essay or even a Test, and attempts to compensate by marking terribly as to give out a low mark to said student who completed the assignment.
Zack: What did you write down when it asked for "Define Gene,"
Tim: IDK, Ms. K hates me so I am going to get a shit mark on that question anyway.
Zack: Yea she is SUCH a bitch marker.
Fred: I love Ms. Hendren, despite our unsually hard test she marks it amazingly easy.
Tim: Wow, she is the opposite of a bitch marker.