LORELAI: Why are you here?
CHRISTOPHER: You’re gonna force me to lawyer up, officer.
In the US, to “lawyer up” is an informal phrase meaning to exercise your right to have legal representation while answering a police officer’s questions.
Christopher is telling Lorelai to back off on asking him questions about why he is there (even though that’s surely a reasonable thing to ask, given the circumstances).
CHRISTOPHER: Are you surprised?
LORELAI: Oh, the teeniest feather could knock me in the gutter.
A play on the phrase, “You could have knocked me down with a feather” to suggest being overcome with surprise and amazement. The phrase dates to the 18th century.
EMILY: Careful, Richard. That canary you ate is going to spoil your dinner.
Emily is referencing the common phrase, “Like the cat that ate the canary”, to mean that someone is looking smug or self-satisfied, especially in a situation where they should be feeling guilty for their actions. The idiom dates to perhaps the early twentieth century.
LORELAI: Okay, how about this? I’ll help you. I love to paint.
LUKE: You love it?
LORELAI: I want to marry it.
Lorelai is inverting the playground insult about a favoured activity, “If you love it so much, why don’t you marry it?”. Of course viewers may well suspect it’s not painting Lorelai wants to marry so much as the man whose place she’s painting.
LORELAI: Do you come bearing pizza?
DEAN: I’m not an idiot.
A play on the phrase “to come bearing gifts”, which originates from the Christmas story as told in the Gospels, where the three wise men come to visit the baby Jesus, bearing gifts of gold, frankincense, and myrrh.
RORY: You’ve met him [Todd] twice.
LANE: But the third time’s a charm.
Third times a charm is the American version of the old saying, Third time lucky. It means that if you have failed in your first two attempts, you will probably succeed on the next one.
The origins of the proverb may be ancient, as the sacred power of things in threes is older than the Trinity, and can be found in Celtic magic and even fairy tales; it is a common idea in many cultures around the world.
SOOKIE: What on earth were you thinking?
LORELAI: That I could still skate.
SOOKIE: It’s not like riding a bike you know.
Sookie is referring to the common phrase that a skill that is once learned and never forgotten is “just like riding a bike”.
Opinions vary as to whether ice skating is just like riding a bike – some people say they easily picked it up after decades off the ice, just a little wobbly to begin with. Others find that after a long break from skating, they have no idea how to balance any more and have gone back to beginner status. Sore legs and feet are common, just as Lorelai is experiencing.