Nerds Speak Klingon: When Comic Book Guy tries to get married to Edna Krabappel it is conducted in Klingon; apparently the guests (sci-fi convention attendees) can all understand it.
Comic Book Guy: Edna, the Klingons have a romantic saying. (speaks Klingon) Roughly translated it means I would kill the children of a thousand planets just to see you smile. Edna: Oh, that is the most romantic thing I've ever heard. Which is kinda sad if you think about it.
Oh, Crap!: Groundskeeper Willie's reaction to seeing shredded red material coming out behind his tractor.
Groundskeeper Willie: Oh my God! I've shredded a child! AGAIN!