@OP: It means item has been sold. Admins use that keyword to search for threads in the classified section to move to the sold archive.
You know what would be hilarious is if from now on we made up some convoluted story behind the origin of "banana" (maybe an acronym?) and a totally different explanation as to what it means and tell that to new players.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE