Oo-mox is the act of massaging a Ferengi's ears (or "lobes"); there is no translation for the word. Because the Ferengi ear is one of their most erogenous zones, massaging the ears causes extreme pleasure and relaxation. (TNG: "Ménage à Troi")
Oo-mox, though pleasurable, can also have dangers. It can be very distracting for a Ferengi and may often be employed by females of other species in order to distract a Ferengi during negotiations or to coerce them into an action they would otherwise avoid. (DS9: "Facets") Such was the case in an early, unofficial encounter in 2151, when T'Pol performed oo-mox on Krem only to incapacitate him with a Vulcan nerve pinch. (ENT: "Acquisition")
Not strictly sexual, oo-mox may also be employed for other reasons, notably as a means to an end. The book Oo-mox for Fun and Profit plays on this tendency. (DS9: "Profit and Lace")
Wealthy Ferengi may employ females specifically for the purpose of providing oo-mox on demand. Despite the semi-erotic nature of the act the females may perform this service in public as an overt demonstration that their employer can afford such a luxury. (DS9: "Family Business"; VOY: "False Profits")
When Quark, Nog, and Rom traveled back in time to 1947 Earth, Nog tricked Nurse Faith Garland into giving him oo-mox, although she did not realize what she was doing, making her perhaps the first human to perform oo-mox. (DS9: "Little Green Men")
Vash has knowledge of how to perform oo-mox. She gave Quark oo-mox when negotiating who got the profits from an auction the two organized. (DS9: "Q-Less")
- In "Bar Association" Rom confesses that he has had too much oo-mox by himself. This may be the only reference to masturbation in the history of Star Trek. (You can probably go deaf if you do it too much...)