The Basis of What?

Jules: What does Marcellus Wallace look like?
Brett: What?
Jules: What country you from?
Brett: What?
Jules: What ain't no country I ever heard of! They speak English in What?
Brett: What?
Jules: ENGLISH, MOTHERFUCKER! DO-YOU-SPEAK-IT?
Brett: Yes!
Jules: Then you know what I'm saying!
Brett: Yes!
Jules: Describe what Marcellus Wallace looks like!
Brett: What, I-?
Jules: [pointing his gun] Say what again. SAY WHAT AGAIN. I dare you, I double dare you, motherfucker. Say what one more goddamn time.