Lobe was a Ferengi term referring alternately to the rims of their ears, and in a colloquial sense, the business acumen of an individual Ferengi. The expression may represent customary Ferengi sexism, as Ferengi women had smaller lobes than men, and were formerly forbidden to participate in business.
Physically, the lobes were a highly sensitive area; they were an erogenous zone that produced feelings of pleasure and contentment when stroked, as in oo-mox, but were also very sensitive to pain. (DS9: "Family Business")
Ferengi would often use lobes to emphasize the intelligence, or lack of it, of a particular business maneuver. Quark regularly told Rom that he didn't have the lobes for business. (DS9: "The Nagus") They could also use this distinction on alien species they encountered – in 2151, while pillaging Enterprise NX-01, the marauders Muk and Grish encountered the Earth dog, Porthos; when their universal translators failed to turn his barking into spoken word, Muk concluded that the animal was a lower lifeform, possibly a food source, but Grish, noting the creature's unusually large ears, wasn't so sure. (ENT: "Acquisition")