What really sets Gilmore Girls apart from other shows of its type is the heavy use of clever, fast-paced wordplay. Really fast. This is potentially an off colour joke, given mum's reaction. The same phrase between peers would imply a certain availability on a Friday night. Perhaps you remember days of the week underwear from your own childhood, or perhaps you're just familiar with the scene from When Harry Met Sally in which Sally details the hilarious and psychotic reasoning behind her last breakup: HARRY: So how come you broke up with Sheldon?...SALLY: Well, if you must know, it’s because he was very jealous and I had these days of the week underpants.HARRY: [Makes buzzer sound]. I’m sorry. I need a judge’s ruling on this. Days of the week underpants?SALLY: Yes. They had the days of the week on them and I thought they were sort of funny. And then one day Sheldon says to me, “You never wear Sunday.” He’s all suspicious, “Where was Sunday? Where had I left Sunday?” And I told him and he didn’t believe me.HARRY: What?SALLY: They don’t make Sunday.HARRY: Why not?SALLY: Because of God.

Lorelai's day of the week pants only go to Thursday. The literal meaning is in Em's answer. But the hidden implication is that Lorelai does not wear pants on a Friday. This sounds like a sexual innuendo. The surrounding context makes the situation sound like a late teen female discussing a younger sibling with her mum. Given that Lorelai is shopping for clothes for her younger sibling, it is safe to assume she is either legally an adult or almost so. It's time to talk about — well, you know. I'm pretty sure my "Monday" pair was yellow. "Wednesday" was definitely purple. After that, I couldn't tell you which day went with which color, but I'll be honest: I always felt a little weird wearing the "Sunday" version. Days of the week underwear have been around longer than you'd suspect. As a matter of fact, your grandmother probably wore them. Underwear started becoming more of a novelty item in the 1950s, thanks to the new availability of fabrics like nylon and Spandex, and that was the decade in which the popularity of MTWTFSS underthings boomed, according to both Skooldays.com and Fact Monster.When your little mans making that jump from nappies and pull ups , it's time to make the first step of dressing more fun by investing in some of our super cute underwear sets. Cute colourful and with designs including Mario, Marvel superheroes and more, he’ll happily put these on which will make getting the rest of his clothes on a whole lot simpler. Marvellous milestones