To make small talk during a game, perhaps comments about the hand in progress, or even misleading comments about one's own play. This can have entirely malicious intent or can also just be harmless chatter, though perhaps annoying to other players.
It refers to what people usually do in coffee houses- make small annoying talk. The only difference is that in Poker it's done at the table during the game usually with the intention of misleading or manipulating opponents.
Coffee houses were popular places for drinking and socialising in England during the second half of the seventeenth and early part of the eighteenth centuries. Competition between them was fierce. Many coffee houses prospered by catering for a specific clientele; some of them developed into important City institutions. Custom forbade women to enter the masculine world of the coffee house.