LORELAI: I’m gonna join the Booster Club, mmkay? The Booster Club, I’m going to boost.
EMILY: Well, the Boosters are a very fine organization.
Booster clubs are common at high schools and universities in the US. They are run by parents as fundraising efforts to boost the school’s coffers, especially to pay for supplies, equipment or trips that the students need.
Chilton seems unusual in only having one booster club. Many schools have two – an academic booster club, and an athletics booster club.