I figured all your classes were stuff like Slaughter 101 and Beheading for Beginners."Jace flipped a page. "Very funny, Fray.

This quote is a humorous comment made by one character, Jace, to another character, Fray. Jace is implying that Fray’s classes are very violent, which is not true. He is making a joke about how Fray’s classes are not related to violence and are instead probably mundane, basic classes.