A tan appearing only on the face, neck, and arms. The rest of the body is untaned, and so uppon removing ones shirt there is a distinct line appearing at the collar and arms. A result of working outdoors in rolled up sleeves, T shirts, or sleeveless shirts.
Depending on the situation, a farmers tan can be positive or negitive. Many chicks like a farmers tan on a guy, and all guys appreciate viewing the distinction between a chicks tanned neck and untanned chest (in no small part because her chest will be visible). However, because a true farmers tan is a product of physical labor, the tan is often disliked by those who distain/fear/avoid work and the real world. (read: A place where utility and integrity is more important than fashion.)