The oldest profession in the world has its origin in old Greece, although it might have been invented well before. See the sandals on the left? Well, they might seem an invention from the late 20th century, but:

Definition: Pornai is the ancient Greek word for prostitutes (porne, in the singular). From the Greek word pornai we get our English word Pornography. Pornai were generally the common whore or streetwalker type of prostitute rather than one of the elite courtesans or hetairai. Some pornai wore special shoes that imprinted a message saying “follow me” (akolouthei) in the sand so that customers would know where to find their services.

Examples:
Male prostitutes would be pornoi. They were considered considerably worse than their female counterparts who were an accepted part of Greek society. Pornai might work in brothels or on the street; they might be freeborn or they might be slaves. They may have been taxed.