Djew is a carbonated, caffeinated, sugared, non-copyright-infringing soft drink used on the Pro boards, especially the Cross'd Roads inns. It comes in ceramic bottles with medium-length necks, shipped in papyrus crates from somewhere vaguely sandy.
In the real world, Djew is ancient Egyptian for "mountain", making it ReeToes' favourite slang for Mountain Dew, her favourite beverage. Blame Mutt for finding out and telling Ree.