In the episode “Lorelai, Lorelai,” in reference to Das Boot.
LUKE: What’s wrong with a boat trip?
LORELAI: Well, I mean, for starters, you’re on a boat… Anything could go wrong! You’re on a boat, in the water, in the middle of nowhere. Haven’t you seen Dead Calm? Open Water? Das Boot?
LUKE: Okay. First of all, I did not purchase a U-boat.
LORELAI: Titanic! Surely, you’ve seen Titanic.
Read more about Das Boot