MICHEL: It was dignified, as most French ceremonies are. Poetry was read, a string quartet played, a ballerina performed.
LORELAI: You drank some Boone’s Farm out of a bota bag and knocked a beach ball around?
Boone’s Farm, originally an apple wine, now a flavoured malt beverage, due to changes in tax law. It’s made by E&J Gallo in California, one of the biggest wine producers in the world. It’s popular with college students because it’s cheap and sold in convenience stores.
A bota bag is a traditional Spanish wineskin or canteen, often made from goatskin. Modern bota bags have a plastic lining and nozzle.
Beach balls are commonly tossed around by US college students on spring break or at graduation celebrations. Lorelai is teasing Michel by pretending that his graduation in France was the sort of drunken frolic stereotypically enjoyed by American college graduates.