LORELAI: Hey, am I too far from the curb?
RORY: Oh, you’re within five feet.
LORELAI: Close enough for jazz.
Close enough for jazz is American slang meaning “near enough, good enough”. It comes from musician’s slang meaning that a particular tuning, for example, would be “good enough (to play) jazz”. It is of course an immensely annoying phrase for jazz musicians.
The Annotated Gilmore Girls 