A phrase used to express the lack of care or interest in the particular topic; usually used in school scenarios, when your teacher assigns you something, dont give a shit, but then finish with an A in the class.
Yeah I haven't done my homework for the past few days, but I still aced the test...
Wow you've been As Serious As Joe lately.
Hey did you read chapters 27 & 28?
No, Ill just read them next week, im taking this As Serious As Joe