In the episode “Farewell, My Pet.”
LORELAI: So, you know that young guy who’s been visiting Mrs. Santiago in room 236? Not her son, her boyfriend…
EMILY: But he’s at least 20 years younger than she is! He’s just a boy! What could they possibly have to talk about?
LORLEI: I don’t think they’re doing a whole lot of talking, if you know what I mean.
EMILY: I certainly do not know what you mean!