Withdrawing from a course in grad school, bad?

[fibonacci]

Let's say you messed up big time and took a course that is impossibly difficult to pass with the minimum grade.  Is it bad to withdraw from a class in grad school?  Let's say I don't even give a crap about teaching in academia after getting a PhD and that I can take a summer course to supplement the credits needed.  What would you do if you knew you couldn't pass an insanely hard class that's not required but one of your electives?

Edited March 15, 2013 by fibonacci

[Miro]

its better that you withdraw from the class that fail it. you cannot retake classes at my school and replace to replace a lower grade. you can however get a W remove from your transcript. I wish i had withdrawn from a class like that last semester.

Even if you want to go to academia, they will not check your transcript, they will care more about your research ideas and your ability to obtain grants. One of my labmates just withdraw from a class after being sick for one week.