As in "riding the grade mule."

One that rides the grade mule cares not about how much he or she absorbs and/or takes back from whatever class; they only care about getting a grade.

Think of it as a mule led by a carrot and stick.
Benny: "My assignments six months late, but I'm still getting 25% credit. It's better than a zero."

Phil: "Fool, you better get off that grade mule."
by VooDooXII January 10, 2007
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