RICHARD: Uh, you wanna narrow that [drink order] down for me?
LORELAI: Hooch is hooch, Dad.
Hooch is old-fashioned American slang for hard liquor, which became common during the 1920s and the Prohibition era. It originated in the 19th century, and comes from the Hoochino Indians of Alaska. One small tribe, who called themselves the Hutsnuwu, had a reputation of brewing their own illicit alcohol which was extremely potent (presumably the information on making spirits was taught to them by Europeans, but nobody knows for sure).
The Annotated Gilmore Girls 