LORELAI: Most of us had first boyfriends like Brian Hutchins … Seventh grade, I’m sitting in the library, walks up, asks me to go steady. I say yes. He walks away and I don’t see him again until the tenth grade when he tries to sell me a dimebag at the Sadie Hawkins Day dance. And he was way overcharging for it, too.
In North America, a Sadie Hawkins Day Dance is one held, usually by schools and colleges, where girls invite boys, rather than the usual convention of boys inviting girls to a dance.
It comes from Sadie Hawkins Day in the Li’l Abner comic strip by Al Capp, an unspecified day in November when unmarried women could chase bachelors, and marry the one they caught. First introduced in a strip in 1937, by 1939 there had been Sadie Hawkins events held at over 200 colleges.
A dimebag is a small bag containing $10 worth (usually 1 gram) of marijuana. Lorelai’s forgetful admirer seems to have either charged more than $10 for it, or put very little product in the bag. Although Lorelai didn’t buy the marijuana from Brian, she knew enough about buying drugs to know he was trying to rip her off, suggesting some level of familiarity with the subject.
The Annotated Gilmore Girls 