Beg, steal, borrow - something considerably less difficult for people who appear to be temporarily embarrassed middle-class Westerners who normally have access to substantial funds than those who don't have any money because they're poor. A Malaysian hostel owner told me when he lost his wallet in Chiang Mai (across the border, a long way north) whilst travelling in the 70s he worked for a month for cash to get home...

For those unlucky enough not to be surrounded by other sympathetic travellers or travel industry workers, "If I can borrow your phone/computer, I can transfer $xx either direct into your account in return for some cash or we can go to Western Union using your ID and my secret MTCN number and split the cash" is likely to work faster than money couriered from overseas.