As they enter the bank, Lorelai says to Emily: "I swear, one of these days, Alice. Pow! Right in the kisser!", to which Emily responds: "Who's Alice?"
The answer, of course, is Alice Kramden (played by Audrey Meadows), the wife of bus driver Ralph Kramden (Jackie Gleason) on the popular 1950s sitcom "The Honeymooners". Ralph used to issue that empty threat when he became frustrated during arguments with Alice, although he never really followed through on his bluster.
Lorelai comments that if they put Paris and Emily in the same room together, the world would implode. They were actually in the same room, though they didn't seem to interact, in the previous episode during the Bracebridge dinner.