Ancient homes were lit after dark with oil-lamps made from clay. Wikipedia has a picture of some Hellenistic and Roman examples. They had spouts for wicks and were filled through holes in the middle of their top faces. The oil would typically be less expensive than that used for cooking and might not smell very nice.
Lamps could be decorative as well as functional. The moulds in which they were typically batch-produced could imprint a design or motto, perhaps a humorous or sexy one. A lamp might have more than one wick, or be unusually shaped. I don't have the reference to hand, but I'm pretty sure one of Martial's epigrams character-assassinates a rival but downmarket satirical poet as (among other degrading things) a peddler of novelty oil-lamps.
Hansen's CEG contains one very rude inscriptional epigram from such a lamp, fired in Sicily in the fourth century BCE. It consists of a single metrical line, running around the edge of the lamp's top surface, and thus circling the hole through which the lamp was refilled with oil. The motto was not part of the mould; instead someone took it from the mould and incised it with a sharp point before it was fired in the oven. This is thus a very personal insult, one surely aimed at a known contemporary:
I AM PAUSANIAS' MOST BUGGERED HOLE.
