It refers to (Q)uentin Tarantino and (U)ma Thurman. They actually thought of the idea together while filming Pulp Fiction. In the diner, Uma's character is telling John Travolta's character about a TV show she was in...
Go 2 mins in.
According to DVD commentary, Uma and Quentin then chatted and created the bride.
From IMDb: "According to Quentin Tarantino and Uma Thurman in the DVD documentary the idea for doing "Kill Bill" began during the filming of Pulp Fiction (1994). The two began talking about the kinds of movies that they would like to do and Quentin said he would like to do a 70's style kung-fu flick. Uma came up with the film's opening shot of her beaten up and wearing a wedding gown."
