What is Thursday Afternoon Girl?
1.
(n) a girl that boys use in order to move on from a past relationship
The origins come from the TV show
RORY: I guess he's taking Thursday afternoons off now. That's not good.
LANE: How is that not good?
RORY: Because that means he's moved on.
LANE: What are you talking about?
RORY: Obviously he's met one of those Thursday afternoon girls.
LANE: What's a Thursday afternoon girl?
RORY: They're those slutty girls that get guys to switch their Thursday afternoons with another checkout guy so they can go do slutty Thursday afternoon things.
See