Butch and Marsellus wake to a blast of water. They're somewhere that appears to be a basement and are both bound to chairs and have their mouths gagged shut with red balls and leather straps. It doesn't look good.
Maynard's security guard pal Zed comes over and they wake up the Gimp, a bondage slave, apparently, who they keep in a locked, wooden chest in a leather straightjacket.
Zed can't choose which one of them he wants to "do first" so he uses the old eeny-meeny-miney-moe and ends on Marsellus.
They chain up the Gimp to watch over Butch while they take Marsellus into the next room and rape him.
Butch, being the strong boxer man that he is, breaks his ties and knocks out the Gimp before heading up stairs.
But just as he's about to leave he turns around, listening to the men raping Marsellus and conflicted over whether to rescue him.
Finally he turns around and after a little searching finds the perfect weapon, a katana.
He enters the room and slices up Maynard when he turns around. Zed tries to go for his gun but Butch stops him.
Marsellus is up now and has a gun. He shoots Zed in the genitals and tells him what's going to happen during the rest of his short painful life. It involves gangsters taking him apart with pliers and a blowtorch.
He calls it even with Butch, so long as Butch never mentions what's happened and leaves LA and never comes back.
Butch leaves, taking Zed's chopper "Grace" (get it?) on the way out.