I'm thinking of sleeping with a professor to help me get a good grade.
That's very improper. I wouldn't sleep with a professor no matter what!
I've heard that this professor is very discreet and he has done this several times before.
It's wrong to bribe people with sex since you are getting unjustly rewarded at the expense of others. Instead of using sex to get a good grade, respect yourself and your body and try to do well in the class using your own scholastic efforts.
I am willing to do this if it gets me a good grade and the teacher isn't bad looking either.
I am glad that you want to get a good grade, but this is a dangerous situation, especially if the professor is known for that. You should get a tutor instead or study more.