MAX: We’re coming out of the restaurant and we’re heading toward our next stop when my brother decides to leap frog over a parking meter.
LORELAI: Why did he do that?
MAX: Middle child.
LORELAI: Poor Jan.
Lorelai is referring to Jan Brady, played by Eve Plumb, a character from the sitcom The Brady Bunch, which showed the daily lives of a large blended family. In the show, Jan was the middle of three girls, and often portrayed as being jealous of her popular older sister Marcia (Maureen McCormick), or otherwise worried about her awkward position as the middle daughter, which sometimes led her into attention-seeking behaviour.
The Brady Bunch originally aired from 1969 to 1974. It was never a big success during its original run, but became a popular staple when it went into syndication, especially among children and teenaged viewers. This success led to several TV reunion movies, and two satirical comedy films in the 1990s. It is now seen as a cultural icon, and is still on American TV in reruns.