LUKE: When you date a girl like Rory, you’re involved with her whole family. Just like that last girl you dated, you were involved with her whole Petri dish.
Petri dish, a shallow, transparent lidded dish that biologists use to grow cell cultures, such as bacteria, fungi, and moss. The container is named after its inventor, German bacteriologist Julius Petri.
Everyone is so horrible about Shane on this show. Even Luke, who (rightly) urged Jess to be nicer to Shane when they were going out, now he speaks of her family as nothing more than bacteria!
The Annotated Gilmore Girls 