In part four of his 10-part travel diary throughout Thailand, Mathew Polly of Slate discusses the history of prostitution in Thailand, how working women from the North claim to use their earnings to purchase buffaloes for their family farms, the Thai concepts of bun kun (honoring debts) and naam-jai (generosity) and how they fit into inter-racial relationships,  the book "Thailand Fever," and bar scams involving the game Connect Four.