19th century British slang for "ass".

Used in the Sandman book World's End by Neil Gaiman page 76:

(Jim comes to the side of the ship where Robert Gadling and the stowaway nicknamed Gunga Din are speaking)

Gunga Din: Ah, young man. You are looking most remarkably well. Is he not looking well Mr. Gadling?

Mr. Gadling: If you say so.

Gunga Din: Ah, but I do say so. We are pondering the sea at this moment, and I was also telling Mister Gadling about the fickleness of women.

Mr. Gadling: And I was telling him that he was talking out of his khyber.

Gunga Din: Ah, yes the entertaining English slang. "Let us group the apples together and pears together." Hahaha. But I tell the truth. Listen. . .