"I hit him hard across the face. I didn't know why for an instant; it was almost as though I were maimed" (79).
This is an ironic statement because Gene isn't the one "maimed" but Finny is. Based on the context of the conversation that took place before Gene hits Quackenbush, the reference must be about the fact that Gene had never learned how to row on a rowing team before. Quackenbush could also be referring to Gene as "maimed" because Gene doesn't care about the fact that he's a senior and just starting to have an interest in managing teams. This signifies that Quakenbush thinks that Gene is slow but also that he shouldn't be the rowing team's manager.