I've determined two major reasons why good grades are not essential this semester.
First of all is the fact that I'm taking three humanities classes that will not apply to my Physics GPA in any form. This means that I can work on convincing grad schools that these classes are not a real reflection on my ability as a scientist anyway.
Secondly, although poor grades in those classes would bring down my overall GPA, I won't be going to school here next year anyway, so no worries about losing scholarships on account of bad marks.
What have you been doing with the first few days of classes?